Step One: Reduce

When the popular phrase “reduce, reuse, recycle” was coined, the idea of reduction was generally aimed at cutting back on the amount of waste you produce. Nowadays, reduction should be done across the board.
Reduce the amount of electricity you use by turning off lights when you leave a room, appliances when you leave the house, running washing machines with cold water whenever possible, using rechargeable batteries, and installing CFLs (the squiggly bulbs) instead of traditional light bulbs.
Reduce the amount of water you use by taking shorter showers, turning off the faucet while brushing your teeth, filling the sink when doing the dishes instead of letting the water run, and filtering your drinking water instead of buying it bottled.
And of course, reduce the amount of waste you leave behind by using biodegradable products more often than plastics, and using as much of an object as you can before getting rid of it. To really cut back on waste though, you should also complete steps two and three.

Step Two: Reuse

Reusing something is exactly what it sounds like. Don't just use something once and then get rid of it. Make the most out of every object, every product, that comes into your possession. Not only will reuse help the planet, but it will also help your wallet. Let's look at a few items that can be multipurpose, shall we?
Glass Jars/Bottles: All kinds of things come in glass bottles now. You've got various juices or sodas, olive oil, vinegar, sauces. Take the labels off, wash them out, and use them again. You can use thinner necked bottles as flower vases. Glass jars can be employed to store homemade sauces or drinks instead of buying new containers.
Plastic Butter Tubs/Yogurt Containers: Plastic and tupperware are generally the go-to items for refrigeration (or freezing, since you should not store full glass containers in the ice box) of leftovers. Instead of buying value packs of plastic boxes with snap on lids, use what you've already got. And when you've used them several times, move on to step three to prevent any leeching of chemicals into the foods you are keeping, because over time and prolonged use, that does happen.
Clothing: A lot of people complain about having older siblings giving them hand me downs, but, for the sake of the natural fibers those clothes come from, embrace it. You don't have to wear the clothes as they were given to. Put your own spin on them. Dye them, rip them, sew fabric patches on them, whatever you want.

Step Three: Recycle

The idea of recycling is kind of obvious. Collect materials that can be broken down and turned into something else, and drop them off at a recycling center. Here's a list of common items that can be recycled:

Newspapers, Magazines, and Junk Mail
Jam Jars, Soda Bottles, and Soup Cans
Shoe Boxes, Paper Towel Tubes, and Orange Juice Cartons
Shampoo Bottles, Milk Jugs, and Plastic Bags
Some recycling centers will even pay you to bring them your items. Payouts usually occur for things like aluminum cans, clear glass bottles, and common plastics. Certain plastics cannot be recycled quite as simply though. And some facilities prefer that you presort the items you bring in. To find out what the numbering system for plastic products actually means, and what materials can be recycled, check out this article.
There are also cosmetic retailers that will recycle lip stick tubes, eyeshadow pallets, and foundation bottles for you. Some places will even give you free products in exchange for turning in your empty containers. Ask your favorite cosmetic retailers if they participate in programs like this.

Step Four: Buy Locally

Now, obviously, when most people go shopping, they buy items from stores within their community, but when I say “buy locally” I don't mean just go down the street. What I really mean is when it comes to buying produce or other natural products, check out your local farmer's market first.
Almost anywhere you go, no matter how big or small, will have some sort of farmer's market, or at least a few road side vegetable stands for you to shop. The thing about these places is that they cater to farms and small businesses that are nearby. Usually, though not in all cases, when you buy from a farmer's market, you are going to be buying produce that has been grown organically. No chemicals, no pesticides. This is good for your body, as well as the environment. It also means that you'll be getting access to fruits and vegetables native to the area, and they might be priced better than the grocery store. My local market even has eggs and milk from a privately owned farm that allows their animals a natural diet.
Larger “chain stores” have to buy their produce from larger farms to supply their shopping centers. This means mechanized farming and, in some cases, liberal use of chemicals to keep the bugs out of the crops. You can always ask for assistance in your grocery store though to find out just what comes from where. And it's always wise to give your fruits and vegetables a rinse before cooking or eating them, just in case.
The only downside to something like this is that some of them are not well publicized, so they can be tricky to find. They aren't always going to be listed in the phone book. If you ask around though, you're show to find someone who knows someone who knows someone else who shops there every week.

Step Five: Discard Correctly

I bet a lot of you didn't know that there is a proper way to get rid of your garbage, did you? Now, most garbage can just be tossed in a bag, placed in the dumpster, and then it gets picked up by a city sanitation worker. There are, however, certain items that need to be disposed of with care.
Auto Fluids: Anything that you put into your car (or that your parents put into their car) needs to be properly disposed of. If you change the oil in your car at home, don't just let the dirty oil leak into the storm drains or the grass. That oil soaks into the ground, and then, into your groundwater. If you're going to simply put it out with the rest of your garbage, at least put it in some sort of sealed container. Your best bet is to have your car worked on by a mechanic who has the proper disposal facilities though.
Electronics: Electronics make up a large portion of the garbage in landfills around the world. What you might not know about electronics though is that a lot of their smaller components are made of plastic and can be recycled. A lot of electronic stores will allow you to drop off damaged items to be recycled or refurbished instead of just putting it out with your trash. (Used batteries and cell phones fall into this category as well.)

Step Six: Clean Up Your Act

Cleaning up is easier than you think. The bottom line is don't litter and don't add unnecessary chemicals to the world around you.
No matter how easy it might seem, no matter how big the temptation, do not discard your garbage on the ground. Always, always, wait for a garbage can. It can seem easy to let a slip of paper or a wrapper from gum to drop to the floor. It's never a good idea though. Even though many people don't get caught, littering can run up a hefty fine in many areas of the world, not to mention, it is very bad for the environment.
Speaking of gum wrappers, you should also resist the urge to spit your chewing gum out when out of doors. Not only is gum a nuisance, getting stuck on shoes or bicycle tires, it is also an eyesore. As gum breaks down on pavement, it loses its color, appearing as black tar-like spots. It can take years for the gum to completely break down, and in that time animals may come across it, thinking it to be food, and try to pull it up. Just like human beings, animals cannot properly digest gum. Unlike humans though who hold gum in their digestive system when it is swallowed, smaller animals like birds can die from the attempt at digestion.

With these six simple steps, you might not be a full fledged “tree hugger” just yet, but you are well on your way to helping out the planet. Another way to clean up? Use environmentally friendly products around the house. A lot of regular old grocery stores are beginning to carry cleansers that don't contain harmful chemicals. There are “green” laundry detergents, liquid dish soaps, glass cleaners. There are also a lot of natural pesticides that you can use in your garden or on your lawn. Every little change you make to keeping your own life cleaner and greener helps out the rest of the world too.