Hi! I'm a learner myself and my advice is - never study grammar ;) It may sound surprising, but, in my opinion, is quite true. After all, I have a teacher who is American and he told me that he never studied English grammar, and he doesn't think about it when he speaks English. Just think about it, it's almost impossible to think about grammar when you have to respond in real conversation.

I think the lesson here is: connect the grammar rules with real examples. I agree with Romen in that studying only the rules will just confuse you. I get suspicious when people claim they learnt English without grammar. I once looked into it and discovered that there are native speakers who say this (and they are lying - they learnt it in school), or non native speakers (and their grammar is awful). I wouldn't turn my back on it. ;)