from personal experience I can tell you the following:
(though I admit different people learn somewhat differently)
I'm not sure how long you are going to stay in PP, but it sounds from your post that "living" means for at least some time.
Definitely take formal lessons, best at good school or personal lessons from someone with real and actual teaching experience.
Focus on grammar, it's the key to almost any language and much more difficult than English grammar (which is super easy), the adjectives and nouns will come along with the grammar.
lastly and most importantly, do anything and everything possible to put yourself into a Spanish speaking environment where you have to learn it by NECESSITY.
(admittedly far more difficult for family than single people, but try anyways. For e.g. if you have a maid, cook, etc, make it a point to try to communicate with her in Spanish no matter how hard it will be at first)
Necessity is the mother of all invention and it never fails. You'll also learn phrases and other stuff you'll never learn in school but piece by piece it will start tying itself together.
Lack of this "necessity" is also why 90% of native English speaking expats I've met everywhere in Latin America speak either very mediocre Spanish to very little to none at all (which shocks the **** out of me)
walk up to your first Dominican who looks like she/he might have a clue and say the following:
hay escuelas aqui en Puerto Plata?
donde estan ubicadas?
gracias por tu ayuda.
relevant suggestions matter though, because i know people who have been going to school for years and their language skills still suck. Just talk to your average American high school student after 4 years of Spanish in high school.
then compare that to the first or second grader who has been sent to an immersion school (those exist here now, what a BRILLIANT idea)