how's this for simple things to do:
energy efficient light bulbs. You can get them cheaper than incandecents for your utility company, or if you're filthy rich, pay the two dollars for one, it saves you money on your electricity bill and less energy is consumed.
errands. do them all at once, make one large trip instead of five small ones. It will save you money on gas, as your engine is more effficient when it is warmed up.
Switch your energy sources. Your energy utility may or may not charge you a small amount to purchase your energy from green sources, like solar and wind, switching mine cost an extra five dollars a month.
recycle aluminium and plastics, easy one. you can even get paid for it, or let the county take care of it for you. Or find a homeless guy, he'll recycle them.
get your car tuned up and change the oil regularly. it wil extend the life of your car, and boost your energy efficiency.
turn off your lights when you're not in a room. saves you money.
turn off the tap when brushing your teeth. less water being treated means more energy for other things.
public transit. actually cheaper than a car if you factor in gas, wear and tear.
These are VERY eassy to do and most of these will save you money.
so if you don't believe humans are responsible for an accelerated greenhouse effect, at least these will save you money.