I flipped and did some buy and hold when I lived in Florida.   

I’ve been starting my research by seeing what is being bought and what is on the market, and live nearby so would like to check out neighborhoods, but am wondering which neighborhoods I should invest in?

There has been a squatter living in it for about 3 years, that refuses access to anyone that I have sent out there to assess the property.Safeguard personnel stopped communication with me last year. 

Rodrigues' recommendation may change this), but my next question would be, are there any cities/markets where 1 of the following are true: 1) You have family/friends that live there, 2) You travel there frequently (either for vacation, work, etc.), or 3) Somewhere else you've lived before AND know the area well?

Since costs of living depend on the area of the country, this will also influence hourly rates.Again though, Google AI can provide answers!

Lived in The Woodlands for almost 19 years now and been investing up in this area for the last 9.

Use tools like the VA loan for house hacking and your Basic Allowance for Housing (BAH) to cover living costs while building equity.

As MFH is dropping there shorts to get and keep full occupancy, offering every spif imaginable, larger units are to accommodate families of size or multi-gen living is a rare inventory. 

I recently purchased my first duplex in Peoria, AZ in September and I am using it as a house hack where I rent out one side and live in the other.

I don't know your living situation but if your paying x,xxx for rent or a mortgage and instead by living in one side and renting out the other you will be paying y,yyy instead and y is less then x that's great, especially if you can rent out your primary residence and make income there too.