I would eliminate auto-erotic asphyxiation completely. Breath play is a fine activity, it's just not something to do alone. There are very few references for this, but it is a problem to be aware of.
http://en.wikipedia. org/wiki/Autoerotic_fatalities


Other than that, have you read the beginners thread?

http://www.bdsmlibrary.com/forums/showthread.php?t=4529