Use bars of soap (not antiperspirant varieties) versus liquid wash.
It's less expensive, and it saves packaging waste. Not to mention that body wash is primarily water, so the fuel costs for transporting it are higher because it weighs more.
The average bar of soap lasts for about 20 showers, whereas a 16-ounce bottle of body wash lasts for an average of 80 showers. But body wash costs on average more than four times as much as soap.