Scratch

I always try to act like I'm talking to just one of my friends, but then I sometimes start with "Hey Homies" or something like that 

Be confident. Act cocky. Most of all, be right. If your right, then it doesn't matter what other people think, they are just wrong. Actually, being funny helps too. Most of all, after practicing your speach, don't think about it. Get 8it ready, then forget all about it right up till you about to go on. Jump in, don't worry. Its that period beforehand that makes you nervous, so just don't let that period happen.
Its like jumping off a cliff, don't think, just jump. (Saying from experiance)

Good luck out there!!