Three Simple Rules
I try to follow three simple rules when I create a new campaign and get ready to throw my players into it.
1) Your players are your campaign - Make the campaign for your players, not for you. Its that simple.
2) Create stories, not a story - Its always a temptation to go all Lord of the Rings with a campaign. DON"T.... you are not Tolkien and this isn't Middle Earth. Creating an epic over-arching super story that binds the characters into an amazing epic adventure is almost always doomed to fail. Create many stories for your world and let your players own ambitions create the epic story.
3) Make the campaign intriguing not cool - If everyone is an uber-cool ninja gangster, and there are a thousand cool races and places and monsters and... well there is only so much cool before it just gets cold. But if you say something like, "this campaign is gonna be kinda Gangs of New York meets Feudal Japan", people may not get it, but they will be intrigued and probably want to know more. I have found that the more players are intrigued by an idea in the beginning the better the campaign in the end.
These usually work for me, what works for you?