Some of the things I do for the environment.

What I do:
Minimize auto usage by walking and/or combining trips and considering if I really need to go there today.  Follow certain safe eco-miling practices such as not wastefully letting the car idle and driving around and around looking for the closest possible parking space.  I don't start the car until I'm ready to move, park at the first space I come to and turn the car off immediately.  And where possible, park where I can pull out without a lot of maneuvering.  Keep tires inflated and car in good running condition. We don't have mass transit of any use to me here, btw. If we did, I'd use it.

Keep the thermostat at 80 in summer with the ceiling fan on. (I live in a beastly hot climate.) I don't use the oven or even multiple stove burners in summer. I believe in one pot meals, which also minimizes cleanup. Keep the thermostat below 70 in winter and use the oven for cooking when it can warm up the house.  And always dress for the climate.

Have a water filter and drink only from glass at home, stainless steel bottles and cups when on the go.  No plastic bottles. I drink tea and other drinks made at home. The bottled beverage industry gets little money from me as well. 

Use only a low-energy notebook computer which I turn off and unplug when not in use.  I have no accessories or chargers left plugged in when not in use.

Grow some of my own food and shop in my local farmer's market.  Carry my own shopping bags and re-use produce bags.  Eat mostly meatless meals and only buy animal products from pastured animals. While I'm not extreme enough to make a big deal about it when eating at someone's home or something, the horrific, inhumane, unhealthy, polluting beef and pork industries get no money from me. And poultry doesn't get much either.  And I try to buy only sustainable fish. I just can't get the hang of cooking those whole Idaho farmed trout. But I'm trying. I also buy a lot in bulk such as dry beans at Whole Foods where I bring my own bags.  I also volunteer at a school garden where hopefully the kids are being encouraged to live a more sustainable lifestyle.

Shop resale. The charity thrift shops near me are really good. Maybe they are near you as well.  Look for those that take consignment. If I bought it over the last 5 years or so and it's not shoes or underwear, it's most likely resale. Especially, clothes, accessories, linens, kitchenware, furniture, etc. And I have a far bigger and better wardrobe than when I shopped more retail. And so much cheaper. There's also yard sales and freecycling websites. Make sure you offer your castoffs to others rather than throwing away.

I make very little garbage.  In fact, I use the bags my cat food comes in and it takes me two weeks to fill the 25lb size bag. I compost food scraps. And I have very little to recycle. Just junk mail, occasional cardboard boxes, the boxes a few food items like tea and pasta come in, vitamin and aspirin bottles, a few glass jars although I reuse many of those.  I bought re-usable bowl covers to use instead of plastic wrap for most leftovers.  They sell them in the same place as the plastic wrap in the supermarket and at Dollar tree. I also use cloth napkins and rags for cleaning.

I also use very little in the way of soap and detergent. You don't need as much as most people use. Why use a cleanser to strip your body of oil, then apply moisturizer?  My clothes aren't very greasy, so why all that detergent?  And I do most of my cleaning with water, rags, vinegar and baking soda.  BTW, you aren't supposed to fill those caps that come with the liquid concentrate detergent.  There are lines indicating how much they want you to use and they are at about half a capful. 

And of course, I have CFL light bulbs, recyclable batteries, turn things off, etc.

These things really aren't tricky or a hardship.  I plan to do a lot more when I get my dream house built out of energy saving methods and designed around gardening and other details of my ideal lifestyle. But right now it's just all designed in my head.  I'm looking to get a new job and relocate out of here. And for now, I rent.