I'm not really sure on the secret to finding good friends, but I can tell you this - when you've found one, put the effort into the friendship or you could lose it forever.
I had made a friend from work and we were both very passionate about music, we'd get together every now and then, go out to concerts, and through just doing that I was able to make friends with some of his friends.
Unfortunately as time went on, because of my anxiety, I turned down one too many of his invitations to hang out and now he barely talks to me.
It's really important to work on a friendship, ie. make sure to extend your own invitations to that friend, don't just expect them to ask you to do things all the time, cause pretty soon they'll question whether you're a real friend or not.