Take the same approach you would if you were going to college and getting a professional degree. 

As the title says, I would like to purchase a few (or a couple of larger) multifamily properties to cash-flow at least $10K per month (ideally $12K/mo.).The criteria are mainly:-B-class properties/locations (i.e. no "ghetto" properties)-Professionally managed by a reputable/trustworthy company (not fly-by-night operations)-Looking mainly in Texas DFW, San Antonio, Austin, Houston) & Wisconsin (Milwaukee and surrounding areas)What kind of investment would this require? 

Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

@Corben Briggs are your books clean so to speak, or do they require adjustments by your tax professional?

If you have a rate of 6% or higher it may be time to reach out to your mortgage professional and see if you qualify or set up a plan for refinance in the future!

I  took over the business over 2 years ago, so now I feel more  comfortable to venture out and seek more.

The homes otherwise have unique dimensional characteristics such as a true 5th floor walk out to the roof deck and I would imagine seeking a variance will give the community organization an opportunity to push back on the height and other design elements that make the homes marketable.

What kind of professional do you recommend I talk to to gain a better understanding?

Be sure not to give my real estate services away Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

These are professionals with additional training and a stricter code of ethics.