Bringing your new kitten home is a very exciting time, but it can quickly turn sad if you do not take the proper precautions and ready your surroundings.  I always recommend that kittens be confined to one or two rooms to start, and then have their territory expanded slowly, with supervision.  Even a small apartment is a big place for a little kitten, and it is amazing how many potential dangers lurk around every corner.  To help keep your kitten safe, and to help minimize your stress, I have written this guide for bringing home kitty!

Start thinking of things as you would if you were bringing home a baby.  You ARE bringing home a baby, one that is actually more akin to a human toddler in mobility and curiosity.  Just like a human baby/toddler, your kitten will want to experience everything in its surroundings, often with its mouth.  Every nook and cranny is a good hiding spot or place to explore.

Every room holds hidden dangers. Many of these we can work around and prepare against, and the others we must just be aware of, and monitor.  This list is by no means all inclusive--get down on the floor and look around, analyze.  This list is just reflects things that we hear about a lot, and is meant to open your eyes and get you thinking!

Bathrooms—one of the best choices to start your kitten in.  They are usually compact, have relatively few places to hide, have less clutter for accidents, and are easy to clean if you have one.

Ideally, get some child-proof locks for the cabinet doors.  Cats have no problem opening cabinets, and they are very amusing for them.  Unfortunately, they are almost always full of danger—cleaning chemicals, razors, beauty products, medicinal items—all of which are potentially lethal for your kitten/cat.  Some child locks are VERY easy to install and use—one finger operation.  If you are worried about the hassle, use one cabinet for all hazardous items and only put locks on that.  Other items may be a nuisance if your kitty enjoys playing with them (toilet paper, bandaids, and tampons come to mind)—but they pose little danger.
Look around and make sure all cleaners, toilet brushes, razors, pills, etc are put away in a safe cabinet or removed from the room.
Get down on the floor and look under the edges of the cabinets.  Often times where cabinets are set together, or in corners, or next to walls you will find gaps that are covered for aesthetics with a false front—kick board on base cabinets, cover boards between cabinets or near walls.  So while it looks solid from most angles, if you get on the floor and look up a bit (as your kitty will do) you can see the gaps and spaces.  Keep in mind your kitten is very flexible and can squish in to very small spaces.  Any gaps you find, stuff them with cardboard or foam—to the point they and hard to get in to at all
Think about putting an old towel down behind your toilet.  Most cats like to hide in unfamiliar surroundings, and behind the toilet is not a bad choice.  It is also cool—even long time friends may venture back here when it gets hot.
Make sure the garbage gets emptied regularly, and make sure everyone knows not to throw away dangerous items in the waste basket here.
Make sure everyone puts the lid down on the toilet.  Toilet water is not safe to drink—chemicals to clean, germs to flush.  It is also a drowning risk—especially for young kittens.  Any cat may jump in thinking it is solid, hit the water, panic, and pull the lid on themselves scrambling to get out.
If you have a shower curtain, take the end and put it up over the bar—it is a fun place for kittens to climb, and can be a hard habit to break later.
Make sure towels don’t hang where they can be swiped if you like them :)  It’s fun to pull them down and sleep or play on them, and they will get snagged.
If you have shelving in your bathroom, or ledges/windowsills, etc. make sure to clear them of all breakables until kitty has run of the house and you know where they tend to hang out.
Avoid using rubber backed mats, especially the first few weeks.  The smell smells like a good place to relieve oneself to cats.
Don’t leave clothes and towels on the floor—your kitten or cat may become confused and use them to defecate. It is harder to stop something that's started than to prevent it in the first place!

Some common things that are very dangerous for your cat in the bathroom: cleaners, medications, tubes of ointments (feel great on teething kitty gums), dental floss, hair ties, rubber bands, toothpaste, toothbrushes, razors and bar soap. 


Your Kitchen:
Sooo many interesting places and smells!

First--plug up all holes and tight spaces, such as:
Under the dishwasher. 
Under and around the refrigerator, and behind it—especially if you have a water hook up!  You will need to move the fridge to see what is behind.  Many fridges have lost their cover panel that goes over the back—so there may be open areas to access the fan motor and other parts.  This is very dangerous!  You can get some screen material or hardware cloth from the home improvement store and duct tape it over the back to keep kitty out—cheap and easy!
Under and behind the stove—especially if you have gas hookups. Again, please take a minute and move the appliance and look to see what is back there.  Just like the fridge, there may be holes in the wall or the appliance itself that are dangerous hiding places.  Even if the gap between the appliance and the wall/cabinet is small, check.  A scared or adventurous kitten (or cat!) can get in to places that look impossible.
Under the sink -- often there is a big hole thru the cabinet for plumbing—which kittens can squeeze in to, potentially getting in to the walls, under your cabinet, and below the floor—all of which is very, VERY hard to access.  Please consider getting some child proof door latches to secure this area, and then utilize it for cleaning chemicals and other dangerous items you need in the kitchen.
Get down on the floor and look under the edges of the cabinets.  Often times where cabinets are set together, or in corners, or next to walls you will find gaps that are covered for aesthetics with a false front—kick board on base cabinets, cover boards between cabinets or near walls.  So while it looks solid from most angles, if you get on the floor and look up a bit (as your kitty will do) you can see the gaps and spaces.  Keep in mind your kitten is very flexible and can squish in to very small spaces.  Any gaps you find, stuff them with cardboard or foam—to the point they and hard to get in to at all.

Other things to consider 

Cats will get on counters.  Your kitten has been started on training not to do this.  Some people encourage the behavior to make feeding easier or other for reasons.  Many people do not want their cats on the counters.  Regardless, until your cat is trained otherwise (and even then occasionally when they think no one will notice!), try to keep your counters clear of dangerous things, tasty things, and breakable things—all which will attract your cat.  Cleaners and cleaning pads, knives, glassware, toothpicks, twisty ties, dishes waiting to be washed…
Kitchens are often full of dangling cords, which look like toys to cats.  They are appealing to attack, chew on, and try to climb.  They are usually attached to heavy objects that can fall and smash kitties, not heavy objects that will fall and break, and electricity which will electrocute and could cause fires with chewed covering or plugs half pulled out.
Be careful with your kitchen waste. It is possible for your cat to become very sick as a result of eating scavenged food.

Bedrooms:

Most box springs have weak, weak fabric over the bottom, and kittens love to get thru it and in to the springs.  Many kittens die from getting smashed or mutilated in there.  Look under your bed and see what’s there.  Fixing this can be as simple as buying an anti-allergen or anti-bedbug zip on cover for a mattress (you are just using it on the boxspring).  If your mattress is supported by slats instead of a box spring, there is nothing to worry about.  Some beds have a wood platform that supports the boxspring, that is safe, too… just look for holes that they can get in to, and cover them with screen or hardware cloth and duct tape.
Remove all breakable items on the shelves, dresser, windowsills until you know where your kitten likes to hang out.
Take the cords from blinds and curtains and tuck or tie them out of the way. Clips work well, or just a loose single knot—just make sure you do it up near the top and out of reach.  Kittens can easily strangle on cords—playing and get stuck and panic, or fall with one wrapped around.   
Keep your closet doors tightly shut.  It is always a good idea to get rid of as many dangers here, too, because kittens have a way of getting in while you are busy dressing.
Cords—phone lines, charging cables, clock power cords… all of these will appeal to a bored kitten overnight.  Remove what you can, look in to wrapping the rest—you can buy cord wraps at most home improvement stores.  PVC pipe works well, too, if you have several in one spot, just feed them thru down the back of a night stand, the wall, etc.  Use 3M Command sticky strips, Velcro strips, etc to fasten them to walls or furniture, and you can peel away later without wrecking the paint!

Living room:

Look for holes under the radiator or wood stove, behind the entertainment center, etc.  Also look under the couch and upholstered chairs, and also beneath the cushions—kittens will climb into the springs and get mutilated if they are open or have holes.  Patch over—use screen, duct tape, fabric, etc.
Pull out sofa beds can also a danger, kittens especially will crawl  in under the sofa cushions and down into the bedsprings.
Watch reclining furniture, kittens love to hide up under the footstools or get in behind thru the loose fabric.  The mechanisms can crush them.
Screen off the fireplace. Make sure if you have a fireplace that the flue/vent is closed.  
Bundle and minimize cords, use a cord keeper or piece of pvc pipe to cover and bundle.

General, whole house concerns:

Secure screens on all windows to help prevent falls, and keep your kitten off balconies, upper porches and high decks.
Securely store cleaning supplies, laundry detergent, bleach, paint and paint thinner, pesticides, fertilizer, disinfectants, mothballs, poisons for roaches, ants and rats, medications, and antifreeze (which is deadly and very dangerous because kittens and cats are attracted to its sweet taste). Make sure you keep these in tightly closed areas so your kitten cannot gain access. Kittens are clever little creatures and can usually figure out how to open cabinets.
Remove poisonous house plants, or place them in hanging baskets that you are sure will be completely out of your kitten's reach. Some common indoor and outdoor plants that are poisonous to cats include amaryllis, English Ivy, narcissus, dieffenbachia (dumb cane), mistletoe, poinsettia, holly, philodendron, azalea, rhododendron, daffodil, daphne, foxglove, bleeding heart, potato, iris, ivy, oleander, rubber plant, tobacco, tulip, clematis, morning glory, and weeping fig. Ask your veterinarian for a complete list of dangerous plants.
Store plastic bags where your kitten can't get inside them and suffocate, or chew or tear them and swallow bits of plastic, which cover the windpipe and are so flexible and light they are very hard to clear. If you let your kitten or cat play with any bag, even a paper grocery bag, be sure to cut the handles. A kitten or cat can get tangled in the handle of a bag and become frightened. In trying to free himself he could be seriously injured.
Keep exposed electrical cords as short as possible and tack them against a baseboard so your kitten can't play with them or chew on them as easily. Use some tape or adhesive strips.  There are also tubular cord covers available at hardware stores, or good old pvc, which you can paint to blend in behind furniture or along walls/floors.
Kittens love to explore and sleep in warm, dark places, especially if they are full of soft stufflike dresser drawers, boxes and closets. 
Always check to see where your kitten is before closing the door of the refrigerator, dishwasher, trash compactor, oven, etc.
Always know where your kitten is when you are using the washer and clothes dryer. MANY kittens die in the most horrific ways in these two appliances.
Whenever you leave home, make a habit of doing a check for the kitten.  Know where he is before you leave.  For the first few weeks shutting him in the room with his litter and making sure she has food and water is a very good idea—especially if you have other pets.  Any accidents are easy to find and clean up, you can make that area “extra safe”, and there is no worry about other pets having a bad day and taking it out on the newcomer.  (It happens even with seasoned pets who love other animals.)
Keep very small items away from kitty’s reach. Sewing supplies like buttons, needles, pins, and thread can hurt your kitten's mouth or internal organs if swallowed. The same goes for nails, staples, screws, beads and aluminum can tabs. Other things are choking hazards.
BITTER APPLE is a great training product for things your cat will not stop chewing on.  I have had no luck with similar products, but Bitter Apple is very useful!  It is safe, doesn’t stain or ruin what it is applied to. Try the pet store or order online.
If you have radiators that get hot make sure you have screens for them.
Supply chasing and safe chew toys, a climbing platform, scratching post and food and water at all times to keep them busy and out of trouble,
Be sure you have a place for the kitten to hide—even a box with a hole cut in the side will do, but kitty condos are ideal and provide scratching surfaces as well.
Don’t put a collar on your kitten—they are strangling hazards and can get caught on even household items.  The “safety collars” are better, but still not advisable. 
If you are using baby gates, be sure the slats or mesh in the gates are not large enough for the kitten to get parts stuck in—head, limbs, etc.
Never give your kitten any medication without first consulting your veterinarian. If you think there is any chance your kitten ate a pill, get them to the vet immediately--most towns have 24hr emergency services.  Among the drugs dangerous to kittens are aspirin and the aspirin substitute acetaminophen, diet pills, sleeping pills and tranquilizers. Make sure these and any other medications labeled "keep out of reach of children" are kept out of reach of your kitten as well. Even vitamins (pet and human) can be lethal.
If the doors to outside need to be opened to move people or things for more than a moment, or if you have visitors, consider putting your cats in a safe room.  Cats can startle, or just be curious, and run out a door that is only open for a moment.
Balls of string or yarn, spools of thread, rubber bands, balls of aluminum foil or cellophane, corks are all things your cat may enjoy playing with, but should only be allowed with supervision. Put them away when you can’t watch—these are all things that have head to many sad vet visits. Be careful to never allow kitty to play with anything small enough to swallow — like buttons, beads or paper clips.  Keep them away from children's toys made of soft rubber, fur, wool, sponge, or polyurethane (Nerf!). If your kitten swallows a small particle of any of these materials, it could cause problems with his digestive system.
Candles and oil warmers are interesting to kitty, and can easily be knocked over by a kitten--a potential fire hazard. They could severely scald/burn your cat. And your home!  Keep these well out of your kitten's reach, and only use when you can supervise.
Keep cupboards and drawers closed. Kitty may jump in and become trapped or injured when somebody closes the drawer/door.
Carefully inspect any toys your cat has access to on a regular basis. These include both cat toys & human toys which may be lying around. Even if they were safe toys—make sure they remain so!  Check for loose parts, strings your cat could chew off & choke on, etc.