I've done way more than the 10,000 hours suggested by Malcolm Gladwell to make you an expert because I grew up doing it with my dad as a kid and now have 30+ years on my own of missteps, mistakes, and successes to learn from.

I wouldn't install IKEA cabinets at my worst friends house......utter crap.

As noted above this won't be a "Big Mistake" however it turns out.

I went high on vacancy because I try to plan worst case, but you are probably right that it’s a smidge inflated.

I realize that I will make mistakes and not everything I do will be the best choice.

Dealing with family, especially free loading family, is the absolute WORST. 

In our experience, the #1 mistake landlords make when selecting a Property Management Company (PMC) is ASSUMING instead of CONFIRMING.

Even though we're a local PMC, we tell everyone the following:In our experience, the #1 mistake landlords make when selecting a Property Management Company (PMC) is ASSUMING instead of CONFIRMING.

What financial mistakes did you make when you purchased your first home?

They are not typically a good deal and many of them use the worst service providers (low bidder) to carry out the repairs.