This is a complicated issue. In my experience, almost as complicated as romantic love. What you say here talks mostly about what you can do, consciously. But there's that whole other side of who you happen to be. Just like we don't get along well with all members of the opposite sex (if we're straight), similarly good friendships just happen sometimes, and the specific traits that bring people together are too complex to describe. And sometimes people, as they grow, grow apart, and sometimes they grow together. 'Chemistry' plays just as important a role in friendships as it does in romance. When it comes to women, mostly young women, there's often an underlying sexual element in their friendship (read Why We Love if you think I'm just wetdreaming! note that it was written by a woman!), and the same was often true for males in ancient Greece. So much of it is cultural, and different people might have different views of what constitutes a proper friendship. Personally I find most relationships - both friendly and romantic - to be awfully distant and cold. People don't reveal secrets, don't expose themselves, because they're worried about getting hurt. And who wouldn't, in this kind of world we live in. I think if people are good, good friendships will naturally evolve from that. So we should concentrate on being good, tho that's a harder thing to do than most people realize (it often requires infinite patience and understanding).