i'm an amatuer fighter, i've never been in a real fight, but i can give you some basic tips i learned over time.

aim for the legs-

try to sweep them to the ground with your heel, or a kick.

keep moving-

don't just stand still and throw punches, that will leave you an open target, move around your enemy and jump around alot.

wear a jock strap-

the ballsack will be the first thing a dirty fighter will aim for, so make sure its protected or you'll go down fast.

keep your hands up-

make sure you have your hands up at all times, this makes it easier to punch and helps you keep your gurad up.

block often-

your enemy isn't like a punching bag, he will hit back, so keep your arms up and block their hits, and when they are open let 'em have it!

expect the unexpected-

don't let your enemy get the best of you, if they seem to do anything funny, stop them, or else you could end up with sand in your eyes.

don't turn your back-

some times it can be tempting to close your eyes or turn your head, NEVER DO THIS! this gives the enemy a chance to strike.

but the most important part of fighting-

avoid it whenever you can, if theres a way you can say "sorry" or talk your way out of it, do it, violence should only ever be a last resort.