What advice do you have for a fantasy author who is building a world to service a single book?

There is a small chance that I will split it in two, but that is doubtful.What advice do you have for a fantasy author who is building a world to service a single book?
make it original. everytime someone hears about a book that's supposed to be the 'next harry potter' they laugh it off. come up with something fresh and people will give it a warmer welcome.What advice do you have for a fantasy author who is building a world to service a single book?
don't give up.
Some sites I stumbled on





http://www.saradouglass.com/createw.html





http://www.writing-world.com/sf/world.sh鈥?/a>





I'll edit this question as often as I can with more links. There was a time when for some reason I had several pretty thorough sites on this subject saved. I've since lost them but I'll do my best to relocate them.
Make rules that are consistent (or else explain why something changes). For example, in Harry Potter, no one really comes back from the dead.
Be creative, use lots of details. Good Luck!
Details. Work it out in your mind and on paper. Create maps so the world is more real to you. If you can ';see'; it then it is easier to write about it. Keep notes so if you forget something you can refer to your notes.