How to study well English grammar?
My advice is to learn English grammar through books. You should read children's books and English books. If not, then you should buy bilingual funny books to read both entertainment and remember the grammar structure used inside. From there, learn, take notes to apply when needed.
And, what is your advice?
you can study well English grammar by your own, doing self study, reading English books and watch English movies, then when there's some words that you're not familiar just consult some people who knows it and can explain it but if there's no people can explain it well, go find Webster or search it .