The best way is to practice. There are several ways to do this. Listening and repeating is the best way for me to learn a language. I also listen to songs in the language I am studying, watch movies and read newspapers and magazines. I try to immerse myself as much as possible in the language. I also find I learn the grammar not by studying text books, but rather by listening and repeating; the correct grammar flows naturally. I hope this helps you.

practice, practice, practice. The only way to perfection. to live in a native english speaking country would be a good way aswell.