in my opinion, you don't have to care about any grammar rules at first.
because any of them without your experience is useless and seems very hard.
you just try to read more though you may not understand.
but when you read, you experience it.
and then, after all this step, open your grammar books, you will easily understand what the books talking about and why they talkig like that.
so grammar is based on your experience, like our chinese, we do not learn why we say that but to learn how to say that first, english is the same.
good luck to you.