Settle in your mind what you want, what your goal is with your writing, and then take steps to reach that goal.
And on to that particular piece of advice—get your story down. Tell your story from beginning to end. Make it exciting. Don’t wear yourself out correcting and re-correcting page one. Once you’re told your whole wonderful story and you don’t think your first page is or first pages are worthy, go back. But don’t make yourself sick of a story before you’ve told it.
Buy Writer’s Market, from the company that publishes Writer’s Digest.
If you’re serious, you tell your story and make it wonderful. You learn how to write a great query letter that will tell an editor cleanly what your book is about, why it would fit perfectly with the publishing house, and why you’re qualified to write it. You will learn how to write a succinct synopsis that excites an editor. Remember, it must tell the whole story—they do not want a synopsis that ends with, “And you won’t believe what happens then!”