The powers I would consider to become a full time crime fighter:
-telepathy
-magnetism a la Magneto
-super speed a la Quicksilver
-teleportation
-manipulation of electronic devices
Any one of those I listed would allow me to fight crime while maintaining a relatively low profile.
As far as making a living, I would try to see how much I can pilfer off of the criminals (I would rob their wallets before they get taken away), if it's enough to survive and be reasonably happy then good. If not I would seek a paying position with the police. Plan C is somehow parlaying my power to money making (i.e. gambling, insider trading, etc).