It's not as hard as you may think. And, it's not as easy as you may think. But, in the end, it's after your book is completed - and published - that the real work begins. Regardless of how you published it, you are still the best person to market your book.
With the publishing industry changing so rapidly - big publishers cutting back on manuscripts, small publishers closing their doors, even POD companies cutting back on personnel, some people may think this is not a good time to write and promote a book.
They would be wrong. Write your book.