I would consider interviewing a few good agents who know the market then getting the properties up for sale.

What it will get you is a TON of interviews with good companies. 

I agree with @Mike Dorneman & @Matthew Paul I also do the prescreen telephone interview and only setup a showing when they meet the prescreen criteria of adequate income, no prior evictions, referrals, no smokers and no pets (in my case).

I call up the PMs and have a conversation with them which is an interview.

I won't repeat for fear of butchering it, but he mentioned a strategy for 1031ing flipped properties.I did a podcast interview a few months ago with him.

Kidding aside, you need to interview Brokerages, at least 3 to 5.....ask questions....and ask questions.

I flew to my market and interviewed PMs.

Meet new client interview them and ask them goals.

What kind of process did you use to vet/interview them?  

Interviewed the owner/property manager on the phone, and I had my dad meet him in person to get a feel for him.