I finally found this great blog that showed a tutorial on how to fold plastic bags into "footballs" to make storage easier and tidier. After doing these, it is worth the few minutes it takes to fold up any bags I bring home from grocery shopping. It does not take long, and it becomes easier to do with repetition. See for yourself how neater it looks!
Tutorial adapted from http://mousechirpy-polkadotpineapple.blogspot.com/2009/03/grandmothers-apron-carryall.html