I know that when I feel I am being followed I do not attempt to confront the person. I get out of the area in the shadows. If the person confronts me and I have no choice but to respond, I would be very brief and ask who they are and why they are questioning me. If they punch me out, then game on, but...we know that Zimmerman did not punch and break his nose nor pound his head into the ground nor did he pull his gun. How do we know that? Zimmerman had grass on his back, a gash on his head, a witness heard screams. The man with the red shirt on the ground was Zimmerman yelling for help per the witness. It was Zimmerman with a gash on his head, a broken nose and grass on his shirt. Now could it be that Trayvon was held at gunpoint and jumped Zimmerman? Then why was Zimmerman beaten up so badly? Now were the screams Zimmermans? Gee. Since he is the one with the gashes and a broken nose, I would have to say yes. If Trayvon had similar injuries, we would know both people could have started the physical fight. Why on earth did a fight happen if Zimmerman had his gun and just wanted to blow Trayvon away? It happened because Trayvon jumped Zimmerman.
When I think I'm being followed, I do my best to get to a safe place. But then, I am a small woman, and I don't have the aggressive tendencies of young men.
I can very well envision a scenario in which intentions were misread on both sides, and the situation went from bad to worse as a result. Martin may very well have attacked Zimmerman because he felt threatened by the way Zimmerman was following; noting that Zimmerman was on the phone, he might have thought that Zimmerman was calling friends for back-up for some nefarious purpose, and decided that attacking was his only option.
Despite the politicization of this story, there is not necessarily a "bad guy" involved.