Hi Skeletoncrew! I know exactly what you mean! I've been itching to write a fanfic for quite a while, but I don't have any time. For me, the idea came to me, and I want to get it down on paper. I don't have all the details worked out, just the main plot. I've written short stories in the past, but I've never tried my hand at fanfics. One of the hardest things (at least, IMHO) about writing fanfics, is that characters already have backgrounds and personalities. You can't really be creative with the characterization, so you have to be creative with the plot. I enjoy doing characterization, which is why this part is so difficult for me

Anyway, I used to frequent
http://www.fanfiction.net during summer vacation. It's full of fanfics, but it also has several helpful links that deal with writing. You might find something helpful there. Best of luck, dudette!