1. Do less laundry.
2. Use an eco-friendly laundry detergent. Use as little as possible to get the job done.
3. To remove stains or whiten fabrics, try using hydrogen peroxide, lemon juice, borax, vinegar, or an eco-friendly bleach-alternative instead of bleach.
4. Use vinegar instead of fabric softener. Personally, I don't use anything.
5. Skip the dryer sheets. Or click here for alternatives that soften, scent and prevent static cling in your laundry without the nasty chemicals of conventional dryer sheets. You can also purchase eco-friendly dryer sheets.
6. If you are in the market for a new washer, get an HE front-loading washer. They use far less water and energy than the old top-loading ones.
7. Wash only full loads. With today's machines, I don't think you need to worry much about separating into like colors -- just avoid washing whites with the darkest colors (especially new fabrics), and you should be fine. One trick I use to achieve full loads: instead of ever washing a load of towels, I use whichever towels smell the least fresh to fill up the load I need to run.
9. Line dry as much as possible. If you use a dryer, run as short a cycle as possible and clean the lint trap first.
10. Purchase and wear natural fabrics as much as possible. When you wash synthetic fabrics (polyester pants, acrylic sweater, polar fleece jacket), thousands of pieces of tiny bits of plastic flake off and get flushed with the wash water into the sewage system. Those bits of plastic never go away. They wash up on distant shores and are ingested by marine animals. According to a recent study, the "ingestion of microplastic provides a potential pathway for the transfer of pollutants, monomers, and plastic-additives to organisms with uncertain consequences for their health."