Read newspapers (Listin Diario, Diario Libre and El Caribe are probably the best written).
Try and learn proper Spanish, and do not, for heaven's sake, try and "sound" like a Dominican...you end up sounding like an idiot, and will not gain a lot of respect,except among the low life..and that will be sarcastic respect at best, after all you have the cash that they want.
Do not try and lisp, like idiot TV and radio announcers do when talking about Mr. Jimeneth, or Mr. Olathabal....leave the "th"s for the Spanish announcers, they don't know any better.
Spanish is easy: Ah eh ee oh ou only vowel sounds... the "rr" is like the TT in cattle or battle, really...
Okay, the verbs are nasty...lots of forms, but we just use three or four of them most times.
But read and listen to the way professionals speak...(I know, some of them are pretty nasty in their use of the language, too.)...If you want good models, find an educated Colombian...they are like the mid-Ohio accent of Latin American Spanish...
End of class
HB
Another thought. If you are into sports, like baseball, tune into the games on television. ESPN and FOX carry games and so does the Cuban channel...You can pick up a lot listening and SEEING...
A lot of NBA basketball is on Spanish language channels too and some of the Spanish Basketball League as well.