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?
Learn English You should read a lot of books and participate in training courses. Or learn it by talking to someone in English, or reading forum topics.
As well as watching foreign films.