Learn the craft. Learn how stories are put together. Write clean, write tight. Tell a good story. Develop a voice. Once you learn the craft then pay attention to marketing, editing. In order to compete in the market you have to know what you're doing.
That said, don't let fear keep you from getting out there. The final say-so in developing a writing career is the reader. If traditional doors close to you, don't let that stop you. Good writers get told 'no' all the time. Just make sure you create the best story you can make.
Hire professionals to help you make a product that can stand up next to traditionally published books. To do that you really do have to do your homework. Go to conferences, take classes and workshops. Educate yourself on the business. Luck has very little to do with success. Talent helps but its not the final factor. What you need most of all is perseverance.