I think it's best to write the article in Micrsoft Office Word (or the equivilant), and see if you can get over 1000 words. If you can get 2-3000 words, you've got people's attention, plus you'll get more feedback on how to improve it and even more shared info on the subject.
As Wright said, you need to have much more than 400 words, as these aren't blog posts. You don't have to publish them the moment you make them, as I'm currently working on a Caligula and Braveheart film review, and I'm stuck for ideas.
Just remember, work on the things you like and know a lot about, then you can stray onto popular topics that you know about ^^