Suggest you do some reading here:
http://landlord.com
Find a lawyer (you'll want your lease to be solid)
If you hire a management company, you can only take $3,500/year off for repairs, if you manage yourself, you can take it all (double-check with your accountant - going from memory). Even if you have 10x that much in out-of-pocket-cash-expenses - $3,500. (Yes, I'm still bitter)
If you hire a management company, manage them carefully. I got burned hard by the last management company - basically a license to steal if you don't watch them.
If you can manage yourself, you can do well. If you're looking for 'auto-pilot' income, keep looking.
My $0.02
YMMV