Just like humans, cats need exercise, and scratching posts provide the ideal format. Cats stretch and pull against the scratching surfaces to limber their bodies, as well as to "sharpen" their claws (by removing the sheaths that cover them). Be generous with scratching posts - cats love and need a variety of surfaces and planes, so scatter a few throughout the house.
Number One Solution to Clawing
Don't even think of declawing your cat for scratching your furniture.
Cats need to scratch, for a number of reasons, primarily for exercise. A cat who isn't allowed to scratch will develop soft, atrophied muscles, and lack the suppleness so necessary to the feline. Other benefits of scratching include relaxation, marking his territory and shedding those old sheaths
Try a Real Tree
If you don't mind "rustic decor," consider giving your cat a natural tree log for a post. They love the rough bark texture, and wood gives exactly the amount of resistance they need. (Be sure to knock off any pests first.) Stand it upright or lay it down and let them roll it while scratching. A wooden sawhorse also provides hours of play fun and scratching opportunities.
Observe Your Cat's Scratching Activity
Many cats have personal preferences as to scratching positions. Observe your cat when he is scratching. things around the house. Does he go after carpeting (horizontal) or prefer the end of the sofa (vertical) Other details to notice include his preferred texture (wood door frames, carpet, cardboard boxes) Also, does he vary his scratching locations, or always return to the same place?
Commercial scratchers come in all sorts of designs, planes, and surfaces, and range from inexpensive corrugated cardboard scratching pads to complex, expensive "Cat Condos" I've selected a few of my favorites to help you decide.