Okay, here it is...Been in more fights than I should tell you youngsters, been stabbed, shat at sprayed with pepper spray, beat up, given the boots and more times than not done well for myself. Here is my three points of advice for you!
1) Take up a striking art, you never will learn how to swim unless you get into the friggin pool! Learn technique, work on sparring with different guys (as has been suggested) and dont drop the Judo/Jujitsu. Try to work out in a gym were you can thump a bit, not common today. Go old school and put on pads and really go for it, get used to taking a bit of a beating and push yourself to be in good shape, really learn the arts techniques ext.
2) Remember the one peice of information and it will keep you alive, you can train all you want, push yourself in the boxing ring/Dojo floor/ Mats/ what have you, plan strategyies and work them for each situation, push your body to hard wire in responses and work on building up power, speed and reaction time......but as soon as you get kicked in the balls, punched in the face or leg kicked...that pretty all much goes to shit! So, in a fight situation you want that all worked into your subconcious and then pray it works out for you. Remember you might win 60% of the fights you get in if you are great, 50% if you are good and 40% if you are really just a good fighter! Any one that says they have won all their fights is eather fighting the Homo squad at school or is full of shit!
3) This is the single most important peice of advice I can pass on to you after 30+ years of street fighting and working the door at bars.....DONT FIGHT! First off no one really wins a street fight. 90% of the time both guys get hurt, just one gets hurt more. You dont get a prize or some guy raising your hand at the end to say you won...both guys walk away and that is the most you can hope for....and sometimes one does not! Like I said, I have been knifed, shot at and had my ass handed to me on several occasions, I have also shit kicked and puss punched a tone of guys in my time, I can honestly say, I have never "won" a street fight, But I have survived a tone of them. My biggest suggestion is to simply not fight. Take up the fight sports for competition, fitness and fun, but if your only purpose is to "win" a street fight.....take up petty point man, the world will be better for it...and you get all those cute pictures to hand around the house