« on: April 21, 2013, 09:57:18 AM »
I think you have had some great advices from the others already - from taking the flash off the camera, having adequate shutter speed, or improving the composition by cropping out irrelevant variables.
Another thing I would add is planning. Basically I would suggest you to get to know about the event as much as you can. From where the people of interest would sit, the position where you can mount/bounce your flash, timing, etc. This way you can be better prepared and know where you should be for a given scene. During your planning phase, I found it useful to survey the location by having the lights both on and then off.
Many people have their own approach, but for me, planning process is key.
Hope this helps.