I haven't tried, really at all, to keep my cats from scratching furniture. I've only got very cheap furniture, and the cats seem to enjoy using more than either my spouse or I enjoy it. I did buy a bed from Ikea about a year ago, and they appeared too excited by the bottom of it, so I wrapped a sheet around it. But other than that bed, they can scratch my furniture.
Artemis likes flat surfaces best, and of the current surfaces in my house, she likes 1) the wide back of a chair 2) a flat cardboard scratcher and 3) the vertical sisal rope wrapped scratching post.
Athena likes vertical surfaces best, and her current preferences appear to be 1) naked (unvarnished, untreated) wooden table legs 2) vertical sisal rope wrapped scratching post and 3) flat cardboard scratcher.
My spouse says they use the sisal scratching post more when I'm not home -- which seems strange to me, but apparently they follow me around when I'm home. It certainly looks well used, more than any surface in our apartment other than the bare table legs. But because of how much Athena likes the bare table legs, I'm going to make sure to have a scratching post that is just bare wood available for her at all times, even if I get rid of the table (the attachment of the legs to the table, completely unrelated to the state of the scratched table legs, is not so good).
I keep meaning to get a flat sisal fabric scratcher; I think Artemis would love it, from her current scratching preferences.