I have a practice in DR, but at the moment my partner is running it, I'm in New York legalizing Dominicans and helping Americans move to DR. i will be back in DR soon though, wife does not like the weather here.
I do not recommend you do it on your own. It is not a complicated process, I can tell you that a complicated thing is sending a rocket to the moon. I assure you this is not rocket science, but you still have to write some legal documents, like the claim of your nationality, you would at least need someone to draft this for you in legal Spanish.
A lawyer can also help you prepare for the nationality test. It's simple, still if you have no idea about basic Dominican history you will not pass.
I remember waiting with my client for the interview a Chinese gentleman who married a Dominican lady coming out of the interview yelling at his lawyer that he wants his citizenship, They lawyer said if you don't know who Juan Pablo Duarte is, and why we celebrate the 27th of February,they can't approve it. His citizenship was not rejected though they simply told him to come back in two weeks knowing the answer to a few questions and his citizenship will be approved.
Getting the right help will save you a lot of time.