Place a rubber band on the on/off switch of the appliance or light you want to remember to turn off once you leave the room or house.
Slip the rubber band on to your wrist after you turn the light/appliance on.
Use the visual of the rubber band as a reminder to turn the appliance off.
Slip the rubber band back on the on/off switch when you turn the appliance off.
Think of an activity that you need to remember to do for that day such as take the garbage out.
Slip a rubber band on your wrist and think to yourself while looking at the rubber band "Take the garbage out." Repeat this a couple of times to associate your rubber band with taking out the garbage.
Every time you look at the rubber band, think to take out the garbage.
Perform your task and remove the rubber band.