Use good lighting, make it seem proffessional. If you can't do that then make sure it has atmosphere.
Remember to mix up real footage with game footage.
Also have some random but awesome segment. That's good for grabbing peoples attention. Make sure it's related though.
If you can do 3d animation i'd throw some of that onto the video. In a none corny way. :p
Finally remember that pacing is vital... oh and dramatic music ! XD







