If your cat is digging in your houseplants, go to a craft store and purchase plastic needlepoint mesh.  Cut a circle that will just fit into the pot, and then cut a line toward the middle of the circle, with a hole in the middle big enough for your plant. Place the circle around the plant so it settles on to the dirt.  For a special touch, place decorative marbles or rocks on top of it.  Another idea is to bury a cotton ball that has been dampened with oil of clove in to the dirt.  If your cat is chewing the leaves, you can mist some bitter apple or cayenne pepper on the leaves.

Every cat in your house should have his own litter box, water and food bowl.

Clean your cat box every day.  This will help to discourage your cat from urinating outside of the box.

If your cat likes to climb, you may wish to install vertical blinds in your house.  If you have pull cords on curtains or blinds, be sure to cut the strings so your cat cannot get hung in the loop.

If your cat likes to unroll the toilet paper, simply put the roll on so the paper does not loop over the top of the roll.

If your cat urinates on carpet or furniture, purchase an enzymatic cleaner to remove the odor.

Never clean a pet stain with ammonia.  This will attract the cat back to the spot.

Don't get a scratching post made of carpet.  This will teach your kitty that scratching all carpet is acceptable.

Declawing your cat is inhumane.  It is the equivalent of cutting off the first part of your finger.  Instead, have your vet teach you how to trim your cat's claws.