I did take care of a friend's Seneca II for a while but my boss was less than pleased with the arrangement so I gave it up. We're still friends. In retrospect it wasn't a very smart thing to do with no insurance for such things. If you're working for a place they'll probably feel the same way.
I would also say don't start your own shop right out of the gate either. Work your way up to that. If I could take back every 100hr I signed for in my first year as a mechanic I would. Luckily no one got hurt and I learned a lot.
Find yourself a mentor, work for a shop that you think really has things figured out, trust me, it'll be worth it in the long run.
Edit: Also, tool control is so important take some time to apply it to your own box even if it's not required where you are, and don't think for a minute that all that fatigue and rest stuff you learn in school doesn't apply to mechanics.