Focusing on keeping the current tenants is a mistake.

I want to get it rented out as soon as possible but I don't want to make the mistake of renting it out too soon and then regretting not having full access for any other necessary upgrades at my own convenience.

Let alone sell it.I, like you, want to help others not make mistakes.

First timer here, I live in Seattle, WA houses here are too expensive to make a mistakes for first timer, so I am considering start small from more affordable areas, like Detroit Metro Area or Cleveland, or maybe other locations more seasoned investors can recommend. 

Mistakes made at the acquisition are made up for over time. 

You typically fall into a deal or two at the start, but then you have to really go to work to keep it going.Biggest mistake most investors make is assuming all properties perform the same, regardless of location, tenant pool, etc.Recommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.When investing in areas they don’t really know, investors should research the different property Class submarkets.

I have learned from this experience and ensured clear communication for any future changes.Despite these past mistakes, I have maintained a stable and productive life.

Your first few few rookie mistakes, your naivete, etc., will all make you pay a price and it's better to do it from a strong point not a tap out point.

The mistake we made was not getting an equity line before buying our next home.

I made this mistake with a LARGE sum of money early on, and even lost some of it completely on high risk investments as I was trying to "play like the big boys".