Facebook is for finding people that you later want to find on linkedin. At least that's how I use it. That and for finding local events. I try not to read the feed. Of course I recently deleted my facebook and started a new one aimed only at business contacts. When I meet someone new on there, I find them and friend them on linkedIn. I post my articles and sales on both. It's a tool. Use it as such.
As for liking things. I like things on facebook. Especially business related. I have a couple of female singers and wanna be models that I am doing design work for and I'll like their photos because I know it gives them a little ego boost and it reminds them that I'm there. I do it from a network perspective. I don't have any friends or potential dating partners on my facebook.
A better question would be, what do you use facebook for?