Collecting and reusing rainwater is a great one.
Make sure that you're buying locally! Even better, start an organic garden and produce food for yourself.
If you have a garden, install a system that directs rainwater to it and reduce the amount you have to water.
Supplement what electricity you consume with alternative, clean sources by: replacing outdoor lights with solar lights; installing a few solar panels or a solar system to supplement power to the home.
Install or open the blinds on any south facing windows during the day to reduce the work your heater must do to keep the temperature up.