Use power strips. It's much more convenient to keep all of your electronic chargers plugged in, but even when not in use, chargers still suck energy! Simply plug them into a power strip and switch it off when you leave.

Unplug appliances or electronics when not in use. 

Turn off lights. If someone isn't in the room, turn it off!

Leave your clothes to dry inside your room on a line or drying rack.  Try placing the rack in the sun (near a window), or near your heater in winter months to maximize the utility of sunlight and heat already being generated. 

Replace old light bulbs with energy efficient bulbs.

Turn down your heat. We have blankets and sweatshirts for a reason...use them!

Open your windows. Opening windows instead of using air conditioning saves a ton of energy! During the day, you can use the natural light instead of using electricity. Plus you can enjoy fresh air and the sounds of nature.

Wash clothes in cold water. It works just as well!

Take cooler showers. Sometimes cooler showers are more refreshing anyway, plus you know you'll be saving energy!

Pull down window shades at night in the winter and during the day in the summer to retain or block heat.

Unless you are disabled, don't use automatic doors. Just push or pull. 

Use an energy efficient refrigerator. You could also just share with your roommates or use one in a kitchennette.

Be social. Instead of all using separate TV's, watch a movie with your friends! Do things in groups in the same room.