I highly agree with the above comment, dont be afraid to use your voice.
If people are messing around, shout at them or if need be, give them a quiet but stern word.
Also in most cases marshals know best. Give your team some encouraging words before and during game. You will find that you get a better disciplinary response if you become "part" of their team not just a marshal.
But the obvious, get on top of intense and possibly dangerous situations Quickly, if you see a player who could put 10 balls into a guys back at point blank, wait until he makes the first, or make sure he calls the surrender depending on your sites rules.
But there should be no S**T regarding goggle lifting in game in those situations Use your position of authority as much as possible.
And finally, yes getting hit does hurt more, because you don't have the adrenaline as much as when you play therefore you do feel the sting a bit more.
But dont let that get in your way, be where you need to be and have fun at the same time