*clean and restock toilets on a regular basis.
*Carryout "water patrols" every 25 minutes or so.
*Restock bars.
*Clean coffee machines.
*Order stores, amenities and alcohol for the next crew.
*Prepare for the next meal service.
*Count and record bar stocks for inbound customs authorities.
*Complete duty free sales and paperwork.
If there is any time left you might get to gaze for a while at a trashy magazine whilst trying very hard to stay awake.
Cheers