Old clothes - old/ used clothes will often get thrown out while still being useable. I would suggest that there are more clear and visible outlines on the condition clothes need to be in for donating and being thrown out.

Energy - energy can be used a lot more than we often need. Turing off lights when you leave a room is a simple way to reduce energy being wasted.

Food scraps - food scraps or even good food is often not disposed of properly. Showing people how to compost and dispose of food correctly would help reduce the amount food scraps in land fill as well as putting limits of some foods to stop good food being thrown out because it goes off too quickly.