Practice your writing and attempt to get small pieces published. If your dream is to have a novel on the bookstore shelves, you will find it helpful to try to get short stories or articles published first. This will help you to learn about structure and to develop a good writing style. It will also help you become more confident and may make potential publishers take you more seriously. You may also find that you have a talent for writing things such as non-fiction articles or children's stories. Buy writers' magazines, women's magazines and local publications and study the market.
Liaise with other writers. Some people find creative writing groups helpful. However, this does not work for everybody. There are many online writing forums that you might find helpful. Some writers find a writing buddy to email regularly about writing. You can ask this person to critique your work and return the favor for her. The informality of this arrangement suits some writers better than a formal writing group.
Prepare your manuscript to meet the highest possible standard. Remember that agents and publishers receive more work than they can deal with. Create a good first impression. Look up the publisher's or agent's guidelines on submissions and follow these to the letter. Many writers who are serious about getting published send their finished manuscript to a reputable writing critique agency. Never send the first draft of your work to the publisher or agent. Edit and proofread it. Ask someone else to proofread it also.