I'm starting off in real estate and I am looking to invest in a single-family house & rent it out - I wanted to know what others think are the best towns & cities for investing in a property for stable rents and appreciation or how do you determine if a city/town is a good place to consider investing in?

He will retire from that this mid December.

I can ask my husband, he's in the process of retiring ADAF if you would like more info. 

My goal is to start building passive income and hope to retire sooner and long term goal to develop generational wealth.

From sfh to small multi family to 20+ units, the larger you go the more stable your costs and returns are.  

Even though at purchase the cashflow is lower its stable and rarely goes bad like some riskier areas. 

We moved to a new state about a year ago and bought 2 STRs as part of our retirement 'plan'.

Air Force, 27 years...about to retire.

You don't want the cash, you want stable paying tenants- and if you are at the notice to quit phase- complete the process.

But I'm commission-only, and love the idea of creating a passive stream of income "just in case" and eventually paying off all debt and retiring at a ripe old age with $20,000/month of pure cash flow and 0 mortgages.