Last week, I picked up a copy of Rob Parnell's The Easy Way to Write Fantasy That Sells. This is aimed more at the beginning writer than someone with more experience, but it's always helpful to review the basics. For me, this book raised a lot of questions about genre.
The introduction summarizes the formula for fantasy as "Hero, artifact, quest." While there is some truth to that, in my opinion, all stories need a protagonist with a goal. In pursuit of this goal, the protagonist will often find something (not necessarily physical) to help her achieve her goal. Therefore, this formula may not be unique to epic fantasy. Of course, as Parnell points out, you could consider all fiction to be fantasy since it's based on imagination. Also, when you look at subgenres of fantasy such as paranormal fantasy, urban fantasy, or steampunk, other elements become more important. Parnell does have a chapter defining the different types of fantasy, but epic fantasy is the focus of this book. Perhaps that's why he thinks a typical book length is 200,000 words. (They don't have to be that long, honest!)
The rest of the book covers worldbuilding, characters, plotting, point of view, and resolutions and sequels. Any of these topics can be the focus of its own book, so Parnell just covers the basics here. There is enough information to get a beginning writer started; more experienced writers may find it more of a review than something new. I still found myself highlighting more than I expected to.
As for the part about selling your fantasy, Parnell seems to think that if you formulate your book to meet readers' desires, that's sufficient to sell it. Of course, writing style, cover, blurb, and other factors make a difference too, but there's nothing about marketing in this book. He includes a list of traditional markets if you want to take that route, and he has links to other online writing resources. It might be worth adding this book to your writing library for the links alone.