How can I prevent my cat from scratching the furniture by providing a suitable alternative like a nail file scratching post?

To prevent your cat from scratching the furniture, provide a suitable alternative like a nail file scratching post. Encourage your cat to use the scratching post by placing it near the furniture they like to scratch, using catnip to attract them to it, and rewarding them with treats when they use it. Consistency and patience are key in training your cat to use the scratching post instead of the furniture.