Legal Compliance: Ensure you're on top of zoning laws, landlord-tenant laws, and that your contracts are solid.

We are a Veteran owned and operated mortgage company.

There is a company out there right now paying 40% annualized and I know an investor who thinks its great, well yeah its great until you lose it all - as never in the history of mankind has a company been able to pay its investors 40% per year on a continuing basis.

My company charges an application fee.

I would give similar advice to someone that wanted to open a restaurant, landscaping company, hair saloon, etc.  

Along with Appfolio, we use Showmojo, Leadsimple, Lowe's and our collections company. 

@Tarik Kafel recommend checking NARM.com for professional and licensed PMCs.Also, here's our copy & paste advice:Encourage you to learn from the mistakes of others - by reading posts here on BiggerPockets about owners not having their expectations met by their current Property Management Company.

I rent out a little mother-in-law apartment in my house, as well as a couple RV pads on my property.

I do have owner's company address with me I got it from the county department. 

The southern/middle part of the country is a great place to invest, not only is it affordable but the landllord laws are very friendly.