I marshalled on Okeechobee this year. Some are talkers, some are not. I would let them do most of the talking, especially after they catch some fish and a little less stressed. The hardest thing for me was 3 days of being on an awesome fishery and watching other people get to fish.
You can't give them advise or point out fish. (I was within fingertip reach of a solid 10 lb bass that my Pro didn't see).
You'll get a list of do's and don'ts at your briefing.
Carry plenty of water, a few snacks or sandwich, sunscreen. I fit my rain gear, save face mask, snacks and drinks all in a small bag. The mask is good even if it isn't cold or rainy. Hitting a bug with your face at 70-80 mph HURTS!
If you draw J. Todd Tucker and he offers you a piece of steak that he cooked in the Big Green Egg, take it!! That was an excellent mid-day snack!
It's a pretty good chance to see how they break down the lake, figure out the fish and even a few still in production type lures.
After the tournament there is a tent setup for the Pro's and Marshalls with refreshments.