Jose,
As some of the more recent posters have stated, it's pretty painless:
1) the day before your trip, call your bank and tell them you'll be traveling to the DR
2) when you clear customs, follow the crowds to the arrivals area. You'll go down a short escalator, then look to your right. You'll see a number of ATMs there. All offer decent exchange rates.
3) when you get into town, ask your hotel for the nearest good cambio.
4) relax, be safe and have fun!
If you are looking to reduce your transaction fees, use a Bank of America card at a Scotia Bank ATM, no transaction fees.
If you're really worried about fraud (to the extent such worrying will impact your trip), then open a separate account that is unlinked to your other accounts, and use that card only. Takes maybe 15 minutes at your local branch over your lunch break.