MotoCaribe wrote a lengthy essay on how to ride motorcycles in the DR: Two Wheels in Paradise: A Definitive Survival Guide to Riding Motorcycles in the Dominican Republic A long, but hopefully informative read.
A good read for new drivers in DR, and a refresher for the rest of us.
While cobra's article is directed toward motorcycles, it can help explain the rules of the road - no matter what you're driving.
I can't find anything with which to take exception. He's mentioned the article's existence in other threads, but thought it deserving of its own.