There is no evidence that Trayvon Martin was doing anything illegal, despite his somewhat checkered youth. (Well, he did nothing illegal until he attacked Zimmerman). My point is: if you have a concealed weapon, you would be wise to exercise extreme caution and to be aware of your surroundings at all times. Getting out of your car while watching/following a suspicious person is not being cautious.
What did he do that was incautious?
IMHO backwards. Getting out of your car without a gun is being not cautious. Carrying a gun when you get out of the car is being cautious. Z is alive, M was not. No contest on who was criminal and who was not, whatever else has unnecessarily been stirred up. Capisce?