I've found that studying ww2 hand-to-hand and some reality based combat stuff does wonders for most. You can learn the ww2 stuff in about 6 weeks IF you have access to a BOB(punching/striking bag that looks like a dude). A street fight is a FAR cry from an MMA fight or a bjj match. I'd suggest boxing and the ww2 hand-to-hand stuff. Also, this is a GREAT forum but there are better places to ask advice about fighting. warriortalk.com is one I frequent a pretty good bit. Take my advice for what it's worth, I'm just a cop. But, that's my .02 and what I've seen that works. One thing you have to remember is this: avoid the fight at all costs and DO NOT LOSE. If you get in a fight, fuck that mother fucker up. Use pepper spray, an impact weapon, gun or whatever else you can. Try to avoid it. Be extremely careful of what you say to the cops when they come to speak with you for fucking his world up. I would make a list of lines to use and rehearse them until you know them well. If you kill someone, your mind will be in a million different places and, honestly, it will fuck you up for a while. Moreso if you do it with your hands. It is important to make damn sure everyone around you knows you tried to avoid the fight at all costs. Unfornutately, it's usually guys asking for advice that start fights to prove themselves. That's all fine and dandy until they run into the ONE guy in the bar who isn't looking for trouble, but damn sure isn't afriad of it. He's the one guy that will punch you in the throat, grab you by the throad and kick you in the balls, break your collar bone, break your fingers while wrestling, poke you in the eyes, spray you with pepper spray and then commence to beating you beyond recognition(do I NEED to go on??), etc... So don't be that guy. Kelly McCann(i think that's his name) has some good videos on reality based combat. Check them out. Also, a knife is your friend. A 3 inch knife will reach some vital targets, a 4 inch knife will reach most vital targets but a 5 inch knife will reach ALL vital targets. Stab early, stab hard and stab often. Always cut above the eyes and on the forearms. Get that bastard to seeing his own blood and he'll change his mind damn quick about what he is doing.
Lastly, all of this was said for ENTERTAINMENT purposes only and has never been used by the author. Nor will it ever be. I am a vegetarian and I avoid confrontation at all costs. The end.