As far as art mediums go, drawing has always been pretty minimal and therefore 'greener' than most, especially if you're talking pencil drawing as opposed to chemical-rich pigments. Paper is a bit of a problem, and there are very few options around for the eco-conscious artist. Many of the post-consumer recycled materials are not artist-quality, having been sourced from poor quality paper pulp to begin with. However mainstream art stockists are carrying more recycled paper, and tree-free alternatives, such as hemp, are becoming more readily available.
The first two 'Rs' of the 'three r's: reduce, re-use, recycle often get overlooked and have the added advantage of being easy on the hip pocket. I recently got some 100% recycled office paper to use for my practice sketches, so I can save the 'good stuff' for serious pieces. I often re-use unsuccessful drawings , working on the reverse or doing sketches in the empty space, or using them as a basis for collage. This is especially useful with expensive heavy papers. I'd like to buy locally produced materials to minimize the environmental costs of transportation, as well as supporting the local economy. My favorite papers tend to be foreign made, like Stonehenge, but there are a few good Aussie art supply companies, such as Art Spectrum.
Oddly, I thought that doing more 'by hand' and 'from scratch' - hanging out the washing, baking, gardening - would take time from making art, but the mental downtime that it gives me, away from tv and computer, with busy hands, actually gives me time to think, and I'm feeling more creative than I have in a long time.