Youve gotten some pretty solid advise thus far, so I am unsure what to say without confusing you. I have been a martial artist some years now, and am loyal to no specific fighting style. I basicaly take what works for me. Getting punched in the nose sucks, sucks bad, and would work pretty reliably on an untrained fighter, but being the first to punch to the face could result in a hasty asswhooping. I haven't been in many streetfights, as a martial artist I believe it is paramount to avoid them at all costs, with great power comes great responsibility, just like carying a gun. So the only acceptable times to fight in my eyes are when you are in immediate danger with no way out, or you are comming to the aid of someone else. With that said I was in a situation with no way out, I am a decent grappler, but don't like going to the ground as I am 6'1" and 140lbs, but most fights end up there. The assailent was substancially bigger than me, and enraged, he threw a punch at my dome, my size allows me much quickness, as does the training i hav had. As his punch was traveling towards my dome, I threw a round house kick to his knee, which buckled. As he fell his punch strayed from target, aleviating me from having to block. He was still facing me, one hand went to his knee, the other to break his fall. He was in a squat when I put my left hand behind his head, and threw an elbow with my right arm to his face. He fell over, I left, fast.
I didn't win because of any move I threw, I won because I was able to think through the adrenaline, and act, not react. A clear presence of mind is the most important thing in a fight, second is agressiveness. Practice mainly with sparring with a friend. This helps you think in the moment.