I've only ever made a couple of vids but here are a few things i've learnt.
Technical
Transitions - effects between scenes / shots
Keep em to a minimum. They're nice but like anything, too much and all you see are the effects.
Make sure you don't try and put the whole thing together in one piece if you are using Windows Movie Maker. I learnt the hard way that the movie won't save if it's too big. I ended up having to split it and glue it back together.
Don't know if this applies to other software out there. Anyways if using WMM once you have a section you really like, save it as a movie, then rinse and repeat with the other sections.Once they are all done stick em together.
Telling a story - -
Have an idea of what you want to say in your piece (plan it, storyboard it) This way you can visualise what you need to film and tell your story better.
Watch other video's, be inventive.
Music - Personally I love having some sort of soundtrack to go with a vid. If you do use one maybe try and pick something that 'goes' with what you are filming and try and sync the action with distinct moments in the track. I found that playing the track while capturing video helps with timing etc etc.
Hope this helps.
