Word man, take your time. I hope to have my first book out this time next year which means I will have to pull some hardcore writing hours. But, if I finish it and read through it and find parts I could alter or remove, or find gaps that would work better with something extra in I will fix it.
If you are trying to write fantasy then you should avoid stories that involve Elfs, Dwarfs, dragons, golden heroic characters with no flaws, pure evil villains... that stuff is all played and won't sell. What sells is gritty realism, tackling world issues in a fantasy world of your making, evil characters who are not so evil, more gray... less black and white, flawed heroes, strong female characters... all this shit sells.
Also, I advise people who attempt to write fantasy to first create their world starting with a basic map. I tried writing without one, improvising on my way and you just end up with too many mistakes. I have a map for my world, finished. I have notes on religion in my world, governments and shit like that. The planning I think is the hardest part, once you've got it down though the writing comes easy.... or at least it does for me.
You can all look for my first book early-mid 2008.