So lets' say that all I care about is gaining experience; what's the best course of action to take? I'm aware that attacking and leaving someone yields more experience than mugging or hospitalizing them; is the gain from this more than one would gain from training in the gym? Naturally, experience tips unrelated to energy and nerve are also encouraged.
...Also, yes, I am trying to get to level 15 as soon as possible so I can start traveling.