The best posts are sturdy and sizable, so the cat can dig in and stretch out. Sprinkle a little catnip on your cat's post or board to pique his interest, then manually place and knead his paws on the surface. You're helping him understand the concept and stimulating the secretions of glands in his feet. This smell will make him want to return for many happy scratching sessions. If he doesn't seem interested, a tactile change may be the key.
Some cats prefer to scratch wood, cardboard, or the backside of carpet.
Don't forget to praise your cat and give him a treat whenever he uses his post or board. You can trim those killer claws. Maintaining short, less destructive nails with frequent trimmings will significantly limit the damage to your sofa or rug. Make It Unattractive Check out the repellent spray and tactile products you can apply to furnishings. You may only have to use one for a couple of weeks to convince your cat that there are better choices when he needs something to scratch.