1. Write because you love writing.
If your goal in writing is monetary success, you may be disappointed. Throughout history, writing hasn't been a 'get rich quick' scheme for most writers. In fact, many famous writers, such as Edgar Allan Poe, died broke and broken. If you are writing for any other reason than you absolutely love writing, you are writing for the wrong reason.
Writing is not like learning to tie your shoes or ride a bike. It is more than typing words on a page. Although writing is a skill that can be learned, the writer needs a blend of talent, passion, and education to make writing a satisfying vocation.
2. Learn the Nuts and Bolts
Even with the popularity of Indie publishing, writers are at the mercy of publishers, editors, and – most of all – their readers.
If you choose a field like technical writing or copywriting, you will want your work to be picture perfect. While you will need to know the mechanics of writing, punctuation, grammar, and spelling, they are just the beginning of what you will need to know to be a successful writer. Learn exactly what is expected in the type of documents you intend to write.
A good place to start is at the Freelance Writing Jobs article on 30 types of freelance writing jobs and how to get them. The article gives you the bare bones of what you'll need to know for each writing discipline as well as what you'll need to do to be considered for each type of writing work.
3. Choose Your Writing Specialty
Every writer doesn't have a great novel lurking in his or her imagination and that's okay. Concentrate on writing what comes easiest for you. There is a whole world of writing outside of the great American novel, especially if you are not an American!
Choose your field and work to become proficient in it: Poetry, technical writing, copywriting, essay writing and so much more. Write in a discipline that sates your appetite for writing. When and if you feel it's time to move on to something different, go for it.
4. Research, Research, Research
Another reason to choose a writing specialty that interests you is that in order to write well, you will need to do a lot of research through reading.
Even a good novel must be researched. For instance, I once received a manuscript set in Ireland. It was obvious the author was unfamiliar with the country. She noted that the housekeeper had a "thick Irish brogue" and talked about the family going into the village for Godfather's pizza.
Well obviously, a native Irish housekeeper would have a "thick Irish brogue" as would her employers. Second of all, Irish villages don't have Godfather's franchises. These errors were both found within the first 10 pages and as such, resulted in a rejection notice.
5. Read, Read, Read
You will need to read books, articles, essays, etc. about your genre as well as those within your genre. In addition to reading material about your field, reviews of books within your genre will teach you what readers expect from their writers: what they like and what they don't.
Anyone who has written an essay or a term paper because it was assigned knows that when writing is more of a chore than a passion, it is very difficult to make progress. In order to write well, you have to like to write and like what you are writing about. Most of all, you will find that you need to be a good reader in order to write.