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 are right. and this is a good directions. Also those who want to lean English properly they have to read a huge vocabulary. They should read English news paper and English grammar books. Thus they can know the rules of grammar.