Honestly I don't know what I'd really do if I had considerable super powers and I was the only one. Overall though I think I'd react like Hiro from Heroes (in Season 1, I haven't seen the others) I would try and live up to the ideal of a paragon of virtue, but it would be hard to figure out exactly what kind of crime I would fight... and how.
I would probably end up like the British Captain Marvel, try as hard as I can to be that paramor of virtue, work within the law and be just to villains. But eventually my power would corrupt me, like all power does and I would probably take over the world as a benevolant but extremely flawed dictator.