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.

Really looking for tips on what to do from investors who have been in this type of situation.

As you alluded to, sometimes a passive note investment purchased for monthly payments “goes south”, and becomes an active participation investment, with plenty of additional capital required for legal fees, forced place insurance, and property taxes.  

What paperwork should I keep a paper trail of to make things like taxes and other situations better/easier for myself?

I’d love to hear your tips, lessons learned, or even beginner mistakes to avoid.

You get to harvest the equity tax free.

Focus on cities with favorable price-to-rent ratios, population growth, and employment trends, such as Des Moines, Oklahoma City, and Charlotte, while considering factors like landlord-friendliness and property taxes.

Approximately 6-8 weeks ago my attorney stated he was unable to get the delinquent tax 'owner' nor the squatters served in this matter. 

In that case you might save taxes building with them.

If you need financial help, ask under the "Finance, Tax, and Legal" forum.