Common house rules/common decency for game night

I know that there are many emotionally-powerful, educational, even cathartic role-playing games out there, but that scene is not for me. Daily life is often too stressful, too draining, too mundane for me to play or run anything but crazy adventures or bizarre investigations.  Therefore, most of the house rules I like to play with are of a decidedly relaxed bent.

Steal, borrow, modify, or comment below:

How to get things from me when I am the GM. "Things" might include XP, equipment, plot hooks for your character, or whatever else I feel like:

• Bring snacks or refreshment. Bonus if they're healthy or homemade. 
• Write a nice backstory for your character that is a paragraph in length. Bonus if that backstory ties into other PCs, in-game NPCs, or the game setting. Additional bonus for longer backstory, up to a couple pages. If it's longer than three pages or so, try to publish that short story instead; I have a life. However, I do like plot hooks!
• Of course, for games where backstory doesn't matter, disregard the above bullet point. 
• Office supplies and gaming accessories for the table. Initiative trackers, dry-erase markers, visual aides, fresh character sheets, etc. Generosity is more than its own reward. 
• In games that have supplemental splatbooks, the GM always needs more books than the players. The GM needs to look at the splatbook to see how horribly broken the content is. If you loan a book to the GM before you use it, or let the GM mine it for plot, good for you!

Things that I will try my hardest not to do:

• Play favorites with players. 
• Conversely, dogpile on a player. 
• Come to game unprepared without at least some adventure content.

Things that you should try not to do:

• Be a jerk to the other players. 
• Suggest a major change in where the PCs are going or what they're doing in the beginning or middle of a session. 
• Challenge the GM's ruling during a session. 

Maybe some D&D-specific stuff later.