Long lists can feel overwhelming, but perhaps you’ll find inspiration here to start with (see the source article for practical suggestions):

Solar panels & renewable energy production • Grey water system • Natural, renewable, and recycled building materials • Cool roof • Solar water heater • Energy Star rated appliances • Native or adapted landscaping • Drip irrigation • Reduced trips to the landfill • Food producing landscape • Natural shading • Low-flow faucets and toilets • Gas free landscape maintenance tools • Programmable thermostat • Smart insulation and ventilation • Rain barrels • No-VOC paint • LED lights • Change habits • Keep materials in the house • Don’t forget to check for rebates!

Source: The Gold Hive ~ A Checklist for Making Green Home Improvements