Here's a few, hoping to learn some more. Please share your ideas!
-Never buying water bottles
-Buying in bulk, rather than buying the same product that has been individually wrapped
-Reusing cereal bags as freezer bags (even better than an actual freezer bag!)
-"If you brake, you've made a mistake"
-Shopping at thrift stores and tag sales
-Using the same bath towel for 1-2 weeks
-The 3 Rs, of course!