Put a little thought into your purchases. There may be green alternatives available for just about everything we buy. For example, there are shampoos and conditioners that use all-natural ingredients (rather than chemicals you can't even pronounce). The natural counterparts to these synthetics are better for you while you wash, and better for the environment once they are washed down the drain.
Be careful when reading labels, though. Claims like ‘all-natural’ aren’t regulated, so check the label of your ‘unscented’ body wash to see if there’s a ‘masking scent’ in it.
One other thing to consider, and this goes for everything you buy, is the packaging. Consider the waste product and opt for something recycled or recyclable. Better yet, get a recipe to make your own, and reuse that old shampoo bottle forever. Here’s some help for the next time you run out of something.