I have learned some of these lessons the hard way lately. Others I have always tried to practice. No matter how these rules have come to me, inevitably I have broken them and failed to be a good friend. I have made these mistakes rarely with some friends and often with others. Some have forgiven me and others never will.
Do not ditch friends. They are for life so be careful about the ones you acquire.
Friends do not need to measure up to your expectations. They do not need to perform to your standards. They do not need to be perfect. Expect to really hate some of the food they lovingly make for you on a regular basis. Expect them to sometimes lose at love and to need you to side with them even if you think they were the source of the problem in the relationship. Expect to marvel at some of their politics and some of their clothing choices. Expect to see them put on fifty pounds and learn to see them as if they were still skinny. Go out to a gay bar with them even if they visually reduce your status. Treat them with esteem when you are socializing with them in a group. Realize that it is only a matter of time before you are the one with no mate, no money, bad shoes, dumb opinions and an extra fifty pounds.
Do not disclose to others the personal and private things you know about them. This is sometimes a spectacularly difficult thing to do. In recent years, an entire protocol has been unofficially developed about how HIV status is disclosed or nor disclosed among friends and acquaintances. If a friend tells you in confidence that he is HIV+ and swears you to secrecy, saying that only you and the doctor know this, you had better be willing to keep that secret to the grave if required. You should keep that secret even if you think that gay men should always disclose their HIV status. You should keep that secret even when you are drunk. You have no right to dictate this decision to anyone else. Consider it an honor and a privilege and a responsibility to have been told this or any secret.
Expect friends to sometimes be a hell of a lot of work.
Regardless, life goes on. I will do my best, as I always have. I think keeping these rules in mind will raise the bar for what constitutes my "best."