The Architect gave me the secret to mind control ;)
I think there are two important things - that may actually be
different aspects of the same thing:
1. People want to feel superior, not inferior. This means don't put them down,
don't insult them - not even in a joking way if you can help it. Say good things
about them, honest flattery if possible, joking flattery if necessary. If you
can help it, try not to make them feel superior at the expense of someone else.
Instead of "Wow, you draw so much better than Steve" say "Wow,
that drawing is really awesome".
2. Try to think of ways in which you can transform the competitive aspects of
your interactions into cooperative relations instead. Like if you're going
bowling or to a pool hall, somebody is definitely going to win - this can work
against #1 above and make someone feel inferior. So stop playing so seriously -
you don't need to win, and you don't need to feel bad if you were focusing on
the social aspects of playing, rather than the technical aspects of the game.
If you can help your friends improve their game, do it (but try not to do it in
a I'm-only-helping-because-I'm-superior way). If you can be a wingman
do it.
Not everyone is worthy of being your friend though. If they're the type that regularly puts you down, ditch them for those that are more worthy.