Oxford Modern English Grammar
Here is a helpful and readable guide to contemporary English Grammar which does not simply present grammatical rules to learn, but shows how the English language works. Once you fully understand that, then you also understand the roles that words play and the ‘rules’ of grammar fall into place.
It starts by explaining the different ways in which words are formed and then demonstrates the ways in which words combine to form phrases and clauses. The book then shows how the phrases and clauses come together to create properly balanced sentences. Take all this on board, and you will have a much broader knowledge of the way that that our language works.
In the process of acquiring that broader knowledge, you will also acquire an understanding of the way in which grammatical conventions work. So if, for example, you are unsure of the difference between a transitive verb and an intransitive preposition here is the book that will explain all such matters for you.