PICK SOMETHING UP.
Sounds really simple, but just like so many other things, if each person did just a little bit, think of the huge progress that could be made! Whether it's a road on your way home, a stretch of Adopt A Highway roadway sponsored by your employer or civic club, or even the sidewalk in front of your house, try to pick up one thing a day and either dispose of it properly, or better yet, RECYCLE IT. And since I'm big on processes, here's my exquisite representation of the various waterfall effects possible as a result this seemingly insignificant action, with an aluminum can as an example:
AND for all you overachievers out there, check out the government's Earth Day website for more tips at home, at work, and everywhere else. Remember: Earth Day, Every Day!