The best choice is to drive you to invest several years of time and energy, constantly accumulate and improve, and give timely feedback and correct demonstration to tell you what is wrong, what is different and what is the right statement. The teacher who has a good accent but can't explain clearly doesn't listen to his explanation, just asks him and imitates him. Those who have a bad accent (not the accent you want to learn), even the natives of Guangdong and Guangxi, don't count on it. Those free courses advertised as funny, deadly and ghostly were not needed at first. Those daily textbooks marked with Chinese phonetic notation are rubbish.
As for how to find training institutions, teaching materials and teachers, the search is online bookstores, city websites and forums.