The best book for grammar is Oxford practical English Grammer book by AJ Thompson with exercise books,use it as a refrence during writing or do exercises of exercise books with the grammer book.Another very good tip for English writing is self proof reading and editing of written paragraphs by first reading the sentence in your mind that whether it sounds good or it matches your subconsious software for English(whatever you have learned since your school age) but sometimes during self editing you will find it difficult to take help from your subconcious software at that time consult a best grammer book as a refrence which i have mentioned above and in the end if u know any good English teacher or CSPS check it from them