This is an advice post in the same vein as my Rules for Writers Who Hate Writing Rules. And I'm pretty sure this is advice you'll be able to take.
There are many methods and techniques to craft a story (like this one about the Snowflake method). There are outline methods and plotting methods. There are even character development methods, but no method can replace actually writing the story. Your characters will develop as you go, and if they show inconsistencies you can always go back and fix them.
Some people get bogged down in all the planning and use it to procrastinate, so don't over-prepare. Once you've got as much as you need to work from, start writing. Let the story lead you. Don't be afraid to stray from the outline. (Sometimes it's more fun not to know what's going to happen next!)
Remember why you started writing in the first place - because it's fun! Because you love it! You love playing with words, exploring your worlds, developing your characters and working up an awesome plot.
People can tell you many things about writing, but no one can teach you how to be creative. If you're a writer, you're already creative. Don't doubt yourself.
Now go play and have fun! (and turn this song up)