Lucky for me, I've not encountered much incident thus far. I've learnt to keep my hands protected with Pit Gloves. Saves you from hot engines and easier pick up. I always keep my eyes on the track and be on my feet. This way, I can better appreciate the situation and be ready to act against anything.
Wow that sucks to hear. Worst marshalling "accident" that happened to me when was a 1/8 nitro buggy flipped over and went WOT while upside down and gave my knuckles alot of tire burn.