I assume the process isn’t too different than investing out-of-state, especially since PR is a commonwealth of the US.

Depending on the state and town you life in really looking into this.

I'm not sure how to find the best cities to invest in but am leaning towards DE as I spent time there and have a little experience with the state. 

As a San Francisco, CA native, I ended up investing out of state back in 2021.

If you pass the practice exams with 90%+ you should have no problem on the state/national exams.

I am looking at options in the near future to take the house my parents currently own off their hands as they will be moving to a new state in the next couple of months.

The combination of the Colibri exam prep and the PSI practice test is what worked for me passing the state exam.

What are the areas in the state best for investment.

The HUD/FHA guidelines state that the crawl space of the home has to be adequately ventilated.

Many OOS investors set themselves up for failure because they don't invest the time to ACTUALLY understand:1) The Class of the NEIGHBORHOOD they are buying in - which is relative to the overall area.2) The Class of the PROPERTY they are buying - which is relative to the overall area.3) The Class of the TENANT POOL the Neighborhood & Property will attract - which is relative to the overall area.4) The Class of the CONTRACTORS that will work on their Property, given the Neighborhood location - which is relative to the overall area.5) The Class of the PROPERTY MANAGEMENT COMPANIES (PMC) that will manage their Property, given the Neighborhood location and the Tenants it will attract - which is relative to the overall area.6) That a Class X NEIGHBORHOOD will have mostly Class X PROPERTIES, which will only attract Class X TENANTS, CONTRACTORS AND PMCs and deliver Class X RESULTS.7) That OOS property Class rankings are often different than the Class ranking of the local market they live.Class A is relatively easy to manage, can even be DIY remote managed from another state.