A lot of waste generates from the soaps we use in the shower. Take advantage of bulk soaps, shampoos, and conditioners that are either sold package free or in paper.
I get a lot of my soaps from LUSH. I keep my shampoo, conditioner, and body soaps in metal containers to keep them from getting wet when not in use. These bars last forever! I can probably get 3-4 months out of one bar and that's if I wash my hair every day. Money saved. I've also been able to find package free soaps at farmer's markets and health food stores.
You could also ditch the shampoo all together by doing the "no poo" method which means using baking soda, apple cider vinegar, or just water in replace of shampoo. It works for some people.