I am most comfortable with long-term rentals, but I would like to try a flip or two to build my capital.

Build your team of people or as Brandon Turner from the Bigger Pockets Podcast calls it your CORE 41.

You'll get a feel for the age of the neighborhoods, the vitality of the commercial buildings, the ease of location, the closeness to jobs.The markets you're describing are more linear, and usually have lower capital appreciation.

I would be happy to share my experience in knowledge in this area (MA and RI) as I continue to look to build my portfolio. 

Wealth Building: Paying off the first STR focuses on cash flow and financial security, while buying another property focuses on scaling and wealth building.

Also any tips for automating this as much as possible and how to protect the property financially and property management would be appreciated.I ALMOST understand the rental arbitrage strategy if building a company scaling with say 30 + units and looking for high short term cash flow.  

You can build a deck around them as well - or not. 

It's a business - acquiring/building, managing, and growing a business. 

Lastly, they like building relationships.

I figured I would use HM for the purchase and DADU build.