I was really hoping to be able to chime in on this post, but @Filipe Pereira and @Scott Passman pretty much nailed it. Regardless, I'm still going to try. :)
I too own a PM company in CT, near the cost line and Westerly, RI. Contractor relationships has to be the biggest part, that can't be stressed enough. I've got plumbers and painters that work at night after working all day somewhere else to ensure turnover happens on schedule. Since I give them tons of work, they give me a great rate, which is then passed on to the owner. The other thing a PM is charged with, in my opinion, is maintaining the asset. This doesn't just mean getting market rent, but also not letting maintenance of the property slide. Not just emergency repairs, but also pro-active repairs like keeping track of the roof, exterior spaces like porches and decks, mechanical, common spaces and grounds. We develop a 1 year and 5 year (and sometimes even 10 year) maintenance plan with most of our clients so they can plan accordingly.
Shop around, not a single one of us do things the same, so you will want to find the best fit. This might not necessarily be the cheapest or the most expensive.
As far as taxes go, we give out 1099s for rental income and end of year expense reports specific to the property to use when filing your taxes.
Good luck out there!
-Dave