During our Eco-club meeting, we went around school and colour-coded the light switches to show which could be turned off by anybody (green), which could be turned off after checking with an adult (orange) and those that could not be turned off (red). We learnt that some lights were often left on unnecessarily and some had to be left on for safety reasons (eg in darker areas of the school such as the stairways).
Next, we could spot-check how well the stickers are working - are green lights being turned off more regularly and we could also colour code other electrical appliances to let everyone know when/if they can be turned off too.