Know how to take constructive criticism.

However, as many will tell you on this website, know your market so you can be more critical when looking at the pro forma.

My experience indicates that solid due diligence upfront on the economics is the critical factor, the tax aspects often take care of themselves with only modest planning.

It is critical to know the condition and rehab costs, but buying low and doing the deal in the purchase helps with overall costs as you enter the rehab phase. 

Regulatory oversight is critical. 

You are getting a lot of encouragement and criticism from both sides.

I've been setting the record straight so many times against unwarranted criticism and ignorance about the country and its state of affairs  (while acknowledging its issues) that maybe the government should make me a honorary citizen!

Bigger pockets is acting like a Deep State actor in my opinion by censoring critical information.

Are there any other critical factors that signal a buyer is serious and capable of closing?

From a lender's perspective, separating personal and business credit is critical for scaling operations while mitigating personal financial risks.