There are three "R's" that are meant to serve as a guide to consumption in the world. Reduce. Reuse. Recycle. These have been tossed around for decades, but it is still only recycle that is actively practiced by a large number of people in this country (though not by Chicagoans).
The thing is they are even listed in order of importance. For emphasis, I'll do the reverse...
More and more common, this is excellent for metals, pretty good for glass and paper, and better than nothing for plastic. Many things can be recycled to various degrees, but in the majority of cases recycling means downgrading, and in all cases it requires energy input to breakdown then reconstitute. So recycle everything you can, but only after doing the next two things.
On the simple side is using grocery bags to pick up after your dog. On the somewhat more inconvenient side: always bring your own coffee mug to fill up at coffee shop/gas station/... Don't get any frickin' disposable cleaning product (wipes, bowl cleaners, etc.): brushes, mops, rags and even sponges can be cleaned (and disinfected) and reused, so knock that crap off!
If you are insane: flatten out and reuse aluminum foil, wrapping paper, ziplock bags, etc. There are better options for many of these things (gift bags instead of wrapping paper, tupperware instead of baggies...), but try and find second uses for anything that you must use that would normally be one shot and done, and trade out more reusable items for as many disposable ones as possible.
Turn off lights, don't run water, use cold instead of hot when possible (laundry). Don't purchase anything that is individually wrapped. Never buy bottled water. Get as much fresh food as possible. Get food that is processed as little as possible. Cancel magazines. Walk and bike rather than drive. Don't use disposable cleaning products (it bears repeating). Don't sanitize every surface every 30 seconds.
What is odd is that, all told, there is a great deal under the reduce category that is quite simple. Moreover, it often means saving money, living a healthier lifestyle, and helping to reduce our impact on the planet. It is win, win, win!
Oh, also, live in a smaller house, don't fertilize, and drive an efficient vehicle. Damn. I knew there was something wrong. Hummers, golf course lawns (and golf courses for that matter) and McMansions need not apply. No matter what "green" crap you add to a 6000 sq ft house, it will never ever be environmentally friendly--are you listening Al Gore? A family of 4 really doesn't need more than 1200 sq ft (or really, even that much).
This nation is not designed in such a manner to make reducing our impact to a sustainable footprint easy. It is--in the limits--damn hard. Reducing, however is the first and best option for achieving sustainability.