I think that they offer a very simple and efficient lifestyle.

Is it still possible to get closing costs refunded if I make energy efficient upgrades like windows/doors?

In terms of choice of entity, an LLC is likely to be your best bet for tax efficiency, all-around liability protection, and ease of operation.

We found all our renters via Roommates.com, Craigslist, and/or postings at our offices/workplace.

Eli, if the resources @Brie Schmidt mentioned aren't available to you - which would be the most efficient route - if you had a target KIND of property in mind ie duplex apartment, 3 bedroom SFR, etc, you'd be going for, then you would pick that zip code, and post a craigslist ad saying you had that kind of property available for rent, just a couple sentences describing it, and see how many bites you get.

I have thrown a lot of cash into my properties in capital and energy efficient improvements for the same reasons.

Tomorrow I'll put the siding on.So, at this point, I would say I am still more of a landlord and energy efficiency retrofitter than pure investor - which in my mind will be the point when I no longer need to do any of my own work.

I'm trying to time my leases better so that they end in the summer and looking for other ways to get more efficient. 

So, I will definitely be asking a lot questions on all the methods used by Realtors for generating leads efficiently.

By having the right team we'll work more efficient and able flip more homes.