Find good role models of speech. Don't imitate just any American. Some Americans mumble, they have "lazy lips" and don't make an effort to speak clearly.For example, in your native language a poet and a computer programmer may speak very differently. Right?
Same thing in English. Who are your role models for American English speech? A football player being interviewed on TV often speaks differently from a lawyer in court. What are your goals? Do you want to sounds like an American rapper or like an American CEO?
