Good for you OP! Spanish is such a rich, beautiful sounding language.
My best bet, aside from full immersion is to first, take lessons in order to learn good foundations and know how stuff works and then, hire a language coach who can help you with your specific request.
Source: I help people doing exactly that. Some want to learn an accent, some want to lose an accent, some people need help getting more confident in their second or third language, etc.