i'm working on that too. i'm having trouble with it. I made an outline that was just under a page long, now i'm working to just put the outline to words.
so far, i'm in the first section of my outline, and i'm well over the 300 word minimum. and don't think there is a maximum length. I know i might be going above and beyond, but i'm really trying to show them I want to go there.
anyway, hope this helps, let me know how yours is coming along. what kind of things are you writing about? i've been racking my brain trying to come up w/ topics. good luck