How should I vet an out of state partner?

[Ruben Goodbear Anders]

Just as the title says, what are some ways to vet a potential partner I have never met? This is for a 20 unit multifamily deal. Wouldn't want to overstep my bounds by any means, however, we are basically getting into bed with each other.

What steps have you taken to vet your partners and also insure that you will have a symbiotic relationship?

Thanks in advance.