To discourage a cat from scratching furniture, several strategies can be employed. Provide appropriate scratching posts or boards and place them near the furniture they usually scratch. Regularly trim their nails to reduce the damage caused by scratching. Using deterrent sprays, double-sided tape, or aluminum foil on furniture can make it less appealing. Positive reinforcement, such as praising and rewarding the cat for using the scratching posts, can also be effective.