Using good debt properly and effectively is mission-critical!

The fact they are complaining online might be an indication the property manager dealt with them properly so be sure to ask the manager for their side of the story.I hope this basic guide helps.

In WI You can require the tenant provide proper paper work from a Wisconsin Licensed Professional to evaluate the need, this is a new change, you do not have to just take their word for it or some quack on line guy in Kalifornia. 

The fact they are complaining online might be an indication the property manager dealt with them properly so be sure to ask the manager for their side of the story.I hope this basic guide helps.

In addition, I am taking an investing class of how to properly analyze a real estate investment.

My guess is the work needed to get it up and running properly, will be significantly more than the purchase price.

But while having grown up in similar areas,.I did not have the proper knowledge or protocols to deal with the tenant base...and so I lost money on a number of those investments.

You still have several options, depending on if you want to invest directly in individual properties or be a bit more removed:Full-service turnkey investment: Should be mostly passive after you do your due diligence and pick a provider, but don't skimp on your homeworkYou choose which props to purchase, but have no control over tenanting choices, some say in large maintenance expensesAvg cost for solid B/B+ prop in Birmingham (and some other markets but this is the one I have data for, since it's my market) is about $100k per door; you'll pay market price for a tenant-ready, fully rehabbed propertyPartnering with someone who does the on-the-ground stuff while you provide capitalCan be passive if your partner really knows their stuff, but more likely you'd be fairly involved with the choices madeMore control since you call the shots with your partnerYou can pick which markets and price points you're interested inPotential for higher returns (ie buying distressed and then forcing equity through renovation) if your partner is experienced and can execute consistentlyInvesting in a syndicateMany investors pool funds to invest in much bigger projects like commercial space or large MFRs, or in larger portfoliosVery passive, investors are not responsible for project vetting or management, but you have no controlMay have higher bar for entry, some syndicates require large investments and you'll need to have liquid cash on handBuying shares in a REITLike an ETF but comprised of real estate investmentsVery passive, but no control over which assets are held in the fundHighly liquid, easy to buy and trade, lower bar for entryEverything is a trade-off between passivity and control, time and money.

If you will sleep better at night by executing your plan, them by all means do it. 

EDIT: To clarify, have your agent schedule a showing and go through the proper steps to go in vacant houses, don't just "go into vacant houses"