Cats are private creatures. Keep it very clean. Scoop daily and make sure that the litter is completely changed and the box washed with soap or bleach every week. Most cats also respond to a penny being shaken in a can. Try double-coated tape on their favorite places on your furniture for a week or two to discourage your cat from scratching there.
Cats hate the sticky feeling of the tape on their paws.
One in 10 Americans has some form of pet allergy. And almost half of people with known allergies are sensitive to pets. Cat allergies are twice as common as dog allergies. But virtually any animal can trigger an allergy. Most allergic reactions to pets are set off by tiny flakes of dried skin called dander, not animal hair.