What Rules should apply when practicing?

This may sound weird but i like sparring with someone much stronger than me so that i will get beaten up and hurt, and therefore i remember not to pick fights with stonger people (stops me accidently thinking i'm immortal, which is what happens if i dont get beaten and hurt once in a while)
Does anyone have any guidlines that should be followed during full contact sparring that is supposed to resemble real life street fights, other that the obviouse, like no killing each other?
The training is for self defence purposes only, not for any tournaments or competitions.
Also does anyone have any good ideas for weights training that will make my punches much faster, ie should i punch with heavy, light or no weights?
Thankyou for any comments.

First of all, full contact sparring on a regular basis is not the smartest thing. We who practice the martial arts are in it to sharpen our skills and to improve our minds and bodies.It's okay to test yourself once in a while but most of your training should be at the medium contact level. However, if you plan on sparring full freestyle the obvious rules should apply. No biting, eye gouging. In my school we allow hair pulling and I personally like keeping groin shots in as long as both are wearing protection. As far as weight training goes, it will slow you down actually. The key to hand speed is relaxation. Tension prevents you from flowing freely and constipates your own motion. If you feel you must exercise I recommend plyometric pushups and other body resistance exercises.

Thankyou for your help,
I do only do full contact sparring occaisionally, as i said just to remind me what pain is so i dont try and defend myself from somone who is obviously too strong.
Could you, or somone please explain what plyometric pushups are and and examples of other body resistance exercizes.
Neither of us wear any protection so naturally we keep groin and headshots out of it
Thankyou for you help, any further help on execize ideas for increasing the speed of my punches would be much appreciated.