Imitation, Shadowing, and Role Models
I'm going to break this one up into two categories: (a) language learning role models, and (b) role models to imitate. Both of them can help you become a better speaker, but in different ways.
Even if they don't have perfect pronunciation, they can help you understand the process and what it takes to improve your pronunciation. Naturally gifted people rarely fall into this category unless they are very aware of the processes that help them speak well, so they would usually be “accent role models to imitate.”
As you watch TV and movies, choose somebody who has your type of voice, communication style, and who you would like to emulate. If you don't know, ask your friends to recommend somebody. You could even memorize parts of movies you like, imitating the actors.