It's such a superior feeling when I walk in my hostel corridor switching unnecessary lights off. And frequently closing the leaking taps in the bathrooms.
If you have bikes that run on fuel, you may use it only for longer journeys. If the distance is short why not use a bicycle which will even make your muscles and health along with environment.
Sometimes it good to place some new plants in the gardens and green-ify much of our views which is so touching to our eyes and also maintain a fresh environment. Remember, We are here because the plants are here.
People often say "Save the earth", but we should say "Save our generations" because the earth will always be there and can recover in the matter of time with new evolved species, Its just threat to our civilization that we should fear and save the environment. Haha, I watched this in "fox history". A wonderful piece of information indeed.