Kitten-proofing your home
When bringing new kittens into your home, plan ahead. Babies are a handful, and this is especially true with kittens. Planning should ideally be done before the babies arrive home; but if this is not the case, they should be confined to a small space (like the bathroom minus the toilet paper) until kitten-proofing is done.
To minimize kitten-proofing, and maximize the fun, kittens should ideally be acquired in twos. Having a playmate decreases the amount of damage a bored cat will do, saves you from being the sole source of attention, and socializes the kitten to others of its own species. Kittens who are alone in a house will find anything and everything they can to keep themselves occupied. When you are home with a lone kitten, he or she will constantly want to play at the most inopportune times: while you are using the toilet, sleeping, etc. He or she will also "sneak-attack" you to get you to play, often using claws and teeth.
Assess your house
You've decided to get two kittens. The next step: assessing your house. Get down on the floor. Yes, lie down on it. You're looking at things from a kitten's perspective now, so it's best to see what they see.
1. Cords and Strings
Cords are very dangerous for a cat. They can be electrocuted just by one bite, and the hum of the electricity mimicks the sounds a mouse makes. Strings, while good toys, should be supervised, as they can be eaten and clog up the stomach and intestines. Strings should always be behind locked doors. Cords should be wrapped together with electrical tape when at all possible.
2. Electrical outlets
Your first inclination is to put baby-proof plugs on your electrical outlets. While this seems safe, it can actually attract a cat to them. Cats will investigate anything that seems like it can move, and the difference in texture and color will be an obvious giveaway. They can (and will) pry the plug off the outlet and carry it off to be used as a play toy.
Look closely at the bookshelves, couches, chairs, and other furniture. Are there spaces between the furniture and the floor? If so, is there exposed hardware or other things you don't want the kittens to get into? Kittens can squeeze into the smallest spaces; even adult cats can get into a space no bigger than your closed fist. They can also climb under an exposed dresser and up the back behind the drawers, hiding in your socks for a nap. Recliners are very dangerous to cats, as they can climb inside them and be squashed when you sit down or unfold the chair.
4. Designated Food and Litter Places
Pick a spot for the food and water bowls that is out of human travel patterns, but still accessible. Once you pick a spot, always feed and water the cat in this spot. Cats are very susceptible to change, and will complain (not always vocally) when their environment is disrupted. The litter box should always be separated from the food and water. You wouldn't like to use the toilet in the same room you eat, and cats don't either. The ideal place for the litter box is in the bathroom, but another quiet spot will do as well. If the kitten chooses somewhere else, retrain it by cleaning with an enzyme-based cleaner and placing the kitten in the litter box when it shows signs of needing to go (tail twitching, squatting).
5. Designated "Cat Places"
Designate "cat places" by putting cat toys, scratching posts, hideways, etc. in clearly-defined areas (corners work well) apart from other furniture. Cats will take any advantage they can get to climb, so avoid putting scratching posts by bookcases.
6. Kitty Deterrants
Never use corporal punishment on a cat. This will confuse them and make them afraid of you. Squirt bottles, jars with coins in them, and other loud sounds can work, if used consistently. Picking the cat up and getting it interested in something else is the best way to "punish". Food, praise, and petting when it behaves is the best deterrant to bad behavior. To stop cats from scratching or jumping on furniture, try covering it with tin foil or double-stick tape. This works for some cats, but is as individual as the cats themselves.
Now you are ready to bring home your new friends! Enjoy them, care for them well, and they will be there for you, purring away for years to come.