1) Stay away from "fanboy" anime that has been overdone. Currently in this category by my reckoning are Cowboy Bebop, DBZ, Evangelion, and Trigun. If you *truely* have an original idea that hasn't been done to death, or *truely* think you can do something better than what has already been done with a current song/anime combination, then by all means, go for it. However, don't expect glowing praise when you crank out the world's 1000th video done to DBZ/Linkin Park.
2) Try to find obscure music. And by "obscure" I mean something that people might still recognize, but is not played every 10 min on a top 40 radio station. A lot of popular music already has a fan-base that asscociates certain feeling and images with the music. Even if your video is *really* good, the preconceptions of your audience may ruin the effect.
3) Pick music that fits. Occasionally, as with the "Hubba Hubba, Zoot Zoot" video done to El-hazard's Jinna, you can get away with doing wacky things and create something truely funny, but usually, if the song's mood and lyrics do not fit the show(s) used in some way, you've created a gap between the music and images that will be hard for fans to bridge.
4) Timing. This takes practice. No one is going to be good at this overnight, but at least make an attempt. Slapping random images to a soundtrack without at least trying to time the cutscenes and action to what the music is doing seriously kills a video. Nothing irritates me more then seeing a video at a contest like this. Most big conventions filter out the drek now-adays, but occasionally one will slip through.
5) Do it for yourself. Making a video that will please fans is great, but don't always set out distinctly to do this. If you are not happy with what your video is doing, then most likely that will come across to the fans as well.
Some of my personal favorite videos (Kusoyaro's "Bachelorette" and D.O.G.'s "A Kiss is Still a Kiss") combine everything I have talked about above to make truely entertaining videos, especially in terms of music (We need *more* Reel Big Fish vids! lol).
Anyway, just my thoughts on it, feel free to add your own or provide a counterpoint, but please, let's keep it constructive for those who want to learn something.
