One of the biggest mistakes is to focus on solely cash flow and achieving a BRRRR.

But still want paid the money promised & made huge mistakes with an insurance claim I had going on a property.

Start small and make your big mistakes early.

Do not mistake low cost for low risk.  

And also where it would be tough to learn the industry over one or two deals because the deal time-frame is so long (I could make mistakes that I didn't recognize until 5 years into the deal).In this case, we're talking about notes.

They lived subprime and are still haunted by mistakes the government made along with greedy lenders.

I do have them sync their bank accounts and credit cards to eliminate human error in entering items, and ask them to avoid putting personal expenses on those accounts.

While this is the cheapest upfront option, mistakes can be costly.

What mistakes did you make?

While 20% down improves cash flow by eliminating PMI, it delays entry into the market, potentially missing appreciation.