Spend time with english speaking people
Stick with people who speak proper English.
Practice, read, write, English-language movies and TV and radio. Maybe an unabridged audio book and a text of the same book and read along as you play the audio so you get used to both the spellings and how words are pronounced?
Elementary , read ...good books like Sherlock Holmes... practice it.
As much as it sucks, it's very helpful to study English using a formal text book.
Remove all the unnecessary vowels, like we did with color, armor, flavor....