Here’s a link to some very good advice on writing!  Check it out!

http://www.wikihow.com/Write-a-Credible-Fantasy-Story

I’d like to make my own comments on their advice: They make very good points and suggestions about many things, but I feel that they put perhaps too much emphasis on planning.  Now of course you want to be constantly stretching and growing your idea and characters, and getting to know your world better and better, but too much planning can really slow you down, and from my experience, the momentum from the excitement of your idea should start to fade after the first few days.  So it’s important to not spend the whole of those precious days going crazy with details.  It’s in putting the pencil to the page (or the fingers to the keyboard) that really turns on that ligthbulb floating above your head.  Suddenly you see where you really want to go and what you really want to happen.  Further, if you give your brain too much space to move around in, it feels obligated to fill the entire space and this will give you more junk than you need or can work with.  Your characters and the truly important people and places will get lost in all that rubbish.  More story ideas than I care to count have been foiled by me getting over enthusiastic about planning.  In end I feel I’ve lost touch with what I want to do.  And there’s an even greater danger.

When you perfect a story in every aspect before you start writing, suddenly you are not worthy of your story.  Upon seeing how epic and amazing this whole idea is and just how perfect it could work out, you’re afraid to touch it.  You’re afraid that in the end it won’t be as awesome as you planned it out to be.  Somehow you’ll ruin it.  It seems like such a big job that you’re overwhelmed.  And really, the way to find the true nature of your universe, the way you want it to be, is to let it unfold in front of you.  It’s an exciting thing to watch.  So don’t try to cram all that excitement in the first two days.  Give yourself something to get you through those deserts you’re gonna come to.  ‘Cause, trust me, there’ll be enough of them.