But the biggest thing is to not make mistakes when you buy.

I'd try to take the time to understand what this property would look like if the numbers come in at a worst case scenario, or at least a worse scenario than what you predict, and see if you are still comfortable with it.  

I know I am making a lot of assumptions/stereotypes but you have to look at your potential customers and be ready for worst case scenarios.

By having some familiarity with it and a support network in place it’ll limit your risk of making a foolish mistake.

In all honesty, I don't want to make a mistake.

What has been your biggest mistake as an investor?

Buy a duplex/triplex, live in the worst unit and rent the other units.

This includes potentially renting a place out in Winter or worst case having a vacant property for 2 months. 

@Robin Brown That's my philosophy, the worst thing they can do is say no!

Best case scenario (or worst case depending on how you look at it) is that the initial price reduction because the sudden influx of build lots hitting market, will be offset by the spike in material and labor prices and you see continued normal growth/appreciation in the market.Its no different than where we are today.