But, the properties that interest me are the ones that will have a nice cash on cash return.

It may sound nice to pay a 5% management fee but the extra fees can add up to be more than the other company that charges 10% with no add-on fees.

Nice Keyword list at the end.....lol.

The reason I’m asking is because the numbers in the midwest pencil out on paper really nicely, however, when it comes to the actual management of the properties the actual returns may be quite lower. 

Nice!

How do you initiate a discussion and back and fourth with the seller without having to send a written offer each time? 

As what may be good for someone may not work for you depending on your style etc. it’s a trial and it took me multiple attempts before I found one that worked hard and could get done what I needed.In regards to a number, I use google voice

@Yi Zhao , you can check out a few that I've looked at that I consider to be nice - rentec direct & rentredi(the owner of this system is actually a member here on BP).

I guess I need to determine my market, style and risk tolerance.

Every company is going to operate a bit differently and you want to ensure that you are comfortable with their operations as well as their style of communication.No company is perfect but a great company will provide great communication to owners and tenants alike and be proactive in refining their systems so when the inevitable hiccups occur there is a plan of action to make corrections and grow stronger over time.