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?
I think it always come under your experience only English is not an tough language to learn but if you feel like that it will definitely very difficult and especially grammars are always came only while you are speaking and learning lot then only you can easily pick up English grammar