1- wash your hands thoroughly after using the toilet (some people do not use soap, which actually sucks)
2- Turn the switch off/take the power cable out if an electric appliance is not in use
3- do not litter
4- dont forget to turn all the lights off before leaving your room
5- use water carefully, e.g turn the tap off if you are brushing your teeth, shaving, or just appreciating yourself in the mirror :d etc.
6- thats about it for now..