I assume you mean half a million dollars. Let's see, If you get an after tax return of 8% on half a million that is US$40,000. Assuming you want to save part of that, let's leave you with US$35,000 per year of interest income. You might do a lot better or a lot worse or both.
First of all, I would be interested in knowing what interests you about the Dominican Republic.
Second of all, we have no idea what your skills set is except that you are fluent in English and Spanish and can be thrifty.
US$35,000 is enough to live on if you are reasonably thrifty. Your first year or two would ordinarly be the most expensive.
What I would NOT do is invest a large portion of my money here until you learn the ropes and understand what you are doing. If you are a fast learner and have good teachers, give yourself at least a year or so depending on the complexity of your new endeavor. Most people would be well advised to wait even longer or even to never venture out on their own.
However, that is not to say that you have to abstain from business dealings or working entirely during your time here while you are learning your way around. Whether you spend it on salary or off salary is up to you, but use it to beat around and investigate. Keep your eyes and ears opened. Learn. Observe. Look for your niche. When you find find your niche and figure out how to capitalize on it, go for it when you are ready.
US$500,00 is a lot of money. It can be hard to earn and easy to lose. Also, US$500,000 isn't much money when you have no assets and are staring retirement in the face.
Best of luck.