I look for boarded up properties and then try to find their former occupants.

Skip tracers cost $75 each time. But there is software out there that can do the same job.

Anyone have experience with this? Any recommendations?

@Scott Chazdon

Best thread I read on it:

https://www.biggerpockets.com/forums/80/topics/659...

Ned the mod recommended Findtheseller and PrivateEye.com but talk to neighbors first since that's free

Be prepared to sift through a lot of junk data looking for the useful stuff. Those databases never get cleaned out. But you'll pretty frequently find something recent in there.