You will be teaching English, right? So just make a real effort to make friends with the other teachers, particularly if they are Dominican as they will be particularly interested in being able to speak English with you and most likely educated. Of course, some of them may be deportees,, but hey, just keep you eyes open and your shields up!
Understand that if Dominicans call you "negra" or "negrita",. they are only using it as a term of address, an observation, not an insult. They might just as easily use "gorda".. in that they feel perfectly comfortable saying things like "hey, you really put on weight!" which we never do!! Also be aware that black Dominicans all straighten their hair, and that if you have an afro, or wear afro style hair, (like one of my Haitian friends did), someone might call out to you "feo",, "ugly" on the street.. That, of course, is their problem, not yours.
Feel perfectly safe in taking the big buses *---in fact this is great way to spend some time and see the city.. just hop a bus and take a seat and start talking to the folks around you. Dominicans are super friendly. They really do love Americans and all have cousins or someone in the States, which to most of them is all inside New York. There will always be someone who speaks English, most likely. You can ask them where you are, and ask them where to get off, and when. All that.
You can join a club with a pool. Gold's perhaps? or the Dominican Fiesta? or the Crowne Plaza? This can be expensive but also make your life infinitely better.
I live in Gazcue and have been here for ten years. Old enough to be your mom, or perhaps *shudder// even your grandma.. so PM me and I will send you my contact numbers and you can come over for coffee and we can meet so that you will at least have a contact. I am a journalist and a private advanced English tutor.
You will really have an experience here .. but there can be some things that can also lead to the occasional melt down.
But it will be a great life experience and good for you for taking the leap!
Welcome to the DR!