The most important issue will be evaporation. Make sure that he understands that evaproated water is not saltwater and only RO
water is used to bring the tank water level back up so that your SG
won't go out of wack. Take a piece of tape and mark the normal tank level and tell him to fill it back up to this level with RO
water only. Second is feeding. Have him feed as little as possible. Better to under feed then to overfeed. If your skimmer is up and running, he will have to empty the cup unless it has a drain tube on it.(tell him to be careful here....
***you should make him a list of things that he should look for.
IE***are the pumps running?
check the level of the tank water
check level of skimmate in the skimmer cup.