If indeed writing is what you want to work on, the most important thing is to... write! The point is you need someone to correct your writing. And another thing is to learn grammar and style and such things, so you should read reference books (not only on grammar but also on writing itself). Reading is of course a very good way to learn how to write. In addition, always pay attention to what you have just written (even if it's just a post on this forum), and always be very careful. Revise your writing and read it four or five times before you accept it. Writing is a beautiful thing and it has its own rules.
Note that this is the opinion of the non-native English speaker.
Nyggus
