"I would like to suggest these points to be implemented while cleaning a Reptile cage. That might be handy for your sister.
1. Remove and clean all rocks, bowls, branches etc.
2. Remove and clean substrate.
3. Wipe down interior with wet paper towel to remove all dirt (a sponge and hot water can also be used here).
4. Use vinegar solution to disinfect the tank by spraying it onto all surfaces and wiping them dry.
5. Place all things back in tank.