Please Help- 40D & 430EX

My son has a game tonight and this will be the real first time trying my 430ex out. I have no idea how to use it. Any tips for me?

I will be using the 40D with the 70-200mm F/4L

Thanks.

What kind of game is he going to be playing? What time of the day? Using your flash you're only limited to 1/250 SS, you can use hi-sync but the distance of the flash goes down dramatically. To freeze action from my experience 1/500 is a good starting point. Any lower you will record some movement and may mistake it for a soft lens or bad camera. If I were you I would ditch the flash and increase the ISO as much as possible so you could get fast shutter speeds. AI Servo and burst shots are your friend with the 40D.

Yes, knowing the game really is important as photographing tiddlywinks is different entirely to photographing football, for example!