I just drive around, an area of interest. tall grass, unkept, shades down are a giveaway. note the address and look it up when you get home (out of state owner, tax database etc).
if it is clearly obvious/eye sore talk to the neighbors. they love talking about what's going on, and may have a name/address/phone etc.
I am a W-2 person, so I made it a point to drive a different street to work each and every day. knew every empty house in the area.