Being selfish is pretty much like treating yourself better, doesn't really mind what other people say, because you know that you're living well, you're treating yourself nice.
On the other hand, being very unselfish, that means at the end you will be the one who is taking all the hits, it just depend on if you can take it or not, because often you have to take those hits alone.
I've tried to be the most unselfish person that I could be, but it ended up that I took everything down on myself.