How do i not care what others think?

I had a couple "best friends" like that in HS and college, who were basically shallow "users". When I realized what they were, I decided they just weren't worth my time and stopped socializing w/them. They would seek me out, but I noticed it was usually because they had nothing else going on or they wanted something. I just kept telling myself that I was better than that and didn't need them and finally it "sunk in". I've been that way ever since and very happy with it. Now I know who my REAL friends are!