I'm with bassnleo...it's not a difficult job, but it is, as stated, thankless.
To repeat what has been said, be prepared. Know your rules. Prior to the event, let the anglers know rules that may be specific to the event, even if you think they know.
My experience came with a competitor speeding in a no-wake zone. After clearly stating the areas and rules in those areas, everyone agreed that they understood. It was a black and white call to penalize the team...and they had winning weight. Some friends of theirs couldn't understand but all of the competitors did and that's what counted.
We don't have any apps or provincial paperwork here in Ontario...yet...so that makes it easier.
I guess it's like being an umpire or ref...know the rules , make a call and stick with it. Good luck.
TJ