I think the biggest mistake new real estate investors make -- be it in Denver or Colorado Springs or any other hot market -- is overthinking things.

We would never accept a contract where the buyer’s preapproval was only from some online company (rocket mtg being the worst, and a non starter for us).

(That would have been a mistake had the asset actually depreciated, precluding any claim for loss, but it didn't.) 

In the worst-case scenario handing back the deed and your risk of loss would be low.

It brings the worst tenants.

Decide if you want to keep the tenants or if you want them out and then either write new leases or see if they are willing to move and worst case, start eviction proceedings.

You want to make sure you have a solid foundation so you don't make irreversible mistakes, but you also don't want to fall into the paralysis by analysis trap. 

So, I made the mistake of listening to my mother to said, "don't buy anything you have to clothe and feed" and I sold my 6 homes and invested $1 million into a syndicated real estate deal for 2 K-Mart shopping centers and lost every exactly $1 million plus another $50,000 for attorney fees.I started earning 20 times as much money when I stopped taking advice from real estate brokers.

Is it a mistake to consider the rural areas that are tied to these metros? 

In the future, always prepare for the worst and hope for the best.