I really like the GM: Best Practices. I think something like this for players could be useful.
Player: Best Practices
Some points could be copied across unchanged (Be a curious explorer of the game in play, Help the players use the game system). Others might need a little or lot of reworking (Convey your character, Engage in an interesting conversation). Then some probably don’t work for players at all, and some new ones may need to be added.