Use a buyer's agent that knows the market, contracts, negotiations, etc.If you really want to learn about investing, get a job in property management. 

While @Phillip Austin mentioned Raleigh is a higher returns its just very much a appreciation market, you will not find rentals that cashflow, so depending on your goals its a good or bad market.

For those who have or had section 8 investments (especially in my market) how would you describe your experience?

All indications here are of a pretty healthy market. 

The STR market here has become way more saturated and competitive especially in San Juan. 

Two properties available in the highly sought-after Gresham Park area—one on-market, one off-market.

So it could take a decade to get to todays market rent. 2) it’s almost impossible if not impossible to non-renew a tenant, especially if you’re not an owner occupant. 3) As a seller, even if I could remove paying tenants I never would without a non-refundable payment from a potential buyer that covers all vacancies for 6 months if they fail to complete the purchase. 4) You MIGHT say as a buyer that’s worth it.

What strategies have worked best for marketing midterm rentals in secondary or smaller markets like Portsmouth?

You could put most of your funds in the stock market and access them when needed for a HML.

There are really great REI opportunities in different markets - markets in the Midwest and Southeast of the country are particularly lucrative - where not only are the purchase prices reasonable for most RE investors, but the homes are turnkey (new builds or completely rehabbed homes, tenant ready, systems 10 years of life remaining on them, property management teams in place) with appreciating home value AND appreciating rent.