I think it's about number of games owned, # of years on steam(?), achievements in games (?), cards from playing games, participating in sales and other events, sign up for the hardware beta and steam group (even if not chosen or chosen yet), do community ambassador tasks:
http://steamcommunity.com/id/rawkryptonite/badges/2I think you just do a certain number of those, it isn't all of them.
Not sure other than that. It just worked out on it's own for me. I don't know what's considered good or eligible for what though.
I sold off all game related cards though, doesn't seem to remove XP giving up the cards.
