It might sound reductionist, but start with the basics, and realize that a lot of people do the basics wrong. The basics are:

1. Reduce
2. Reuse
3. Recycle

In that order. That's the part people screw up the most. They want to start with recycling, then move to reuse, and THEN reduce. In addition, there's also

{:start="4"} 4. Renew

In which you take into consideration replenishing the earth with the resources you've consumed.