Focus on absentee owners and start with the ones who live the farthest away and only own one property in the area since they have the least use for the property.You can also drive for dollars, looking for anomalies of disrepair and then look them up in the tax records and use a site like Spokeo to do cheap skip tracing.

I would say definitely do not in almost all cases because it's very easy to manage one property.

Buying two rentals in one year can be a challenge, but there are creative ways to make it happen:House Hack the Duplex: Buy the owner-occupied duplex first.

Stairs are the only way to get in, no grab rails in the bathroom, ramps that are too steep, etc.From what I've read, all commercial businesses/buildings (including ones before the ADA was passed) have to comply with the rules, unless it would be outrageously tough to fix (like installing an elevator in an already built building).Are all these local business just not complying and taking the risk, or am I missing something? 

Saying it wasn't in the lease or @Kevin Sobilo saying it just comes down to one person's word against another would negate virtually every crime.   

Subject: Status of Your Rental Application Dear xxxx, Thank you for your interest in the rental property at xxxxxx.

This is critical for protecting yourself, your property, and your neighborhood.Here’s why:Safety Concerns:Skipping checks could allow someone with a serious criminal history—like a sex offender or violent felon—into your property.

Quote from @Marembo Alexandre: One property at a time.

Apparantly that didn't work out for them either as they sold all their properties a couple of months later.

to get more than one - or even more than two?