Did you know that by just getting to know the layout of your grocery store will save you money? Not loads, but some. The better you know where things are, the faster you can get to the things you want, and the better you can avoid things you don't really need.
I go so far to write up my grocery list items in the order that they are laid out in the store. As I cross items off of my shopping list in order it is a neater process and I am less likely to miss items. I have been going to the same stores for many years and so have a pretty good idea of how things are arranged.
If you are in a new neighborhood, some stores have printouts of the store layout available just for the asking. And it doesn't have to be an exact science. Most stores have produce first, the dairy items altogether, paper products and cleaning supplies last.