Join a writer's club or critique group. Your public library should know the active groups in your area. You'll receive helpful critiques and encouragement. Research what the market is buying . Always send for a writer's guide and sample copy before submitting.
Magazines are much easier to break into.
In fact, I'd suggest you do not attempt a book until you've established a good publishing track record in magazines. If you want to make money, become a greeter at Wal-Mart rather than a writer. Fewer than 5 percent of writers actually make a living at it. Writing offers great satisfaction, but little money. Most of all, be persistent as well as patient.