Theirs a couple of things you can practice at home these are essential skills that will serve you well thought your career,of course the higher you climb the career ladder the less you will use them,but at least you will have the experience of doing these tasks and know what they entail.
1) coffee/tea making,not just making the beverage correctly but be a being able to remember a complicated brew order,prepare it and deliver the correct beverage to the correct person will gain you more Kudos than someone who just slops 6 coffees and 6 teas into mugs and shouts "TEAUP ",leaving everybody to sort out half of the job you were ask to do
2)safe operation of sweeping equipment.learn how to use a broom correctly and efficiently,practice with different types and learn were a soft bristle broom is better than a stiff bristle,also practice the transfer between broom-dustpan-bin .You might wish to follow this up with mopping the floor.
Having a good knowledge of the above will prove invaluable in your first few days weeks months years working backstage.