Yes, there are several little things you can do to make a difference.
Try carpooling, this will help reduce the amount of fossil fuels going into the atmosphere.
Whenever you use electricity, you help put greenhouse gases into the air, so turning off lights, the television, and the computer when you are through with them.
Also, planting trees is fun and a great way to reduce greenhouse gases because trees absorb carbon dioxide (which is a greenhouse gas) from the air.
Finally, don't forget about recycling.