If you fail to plan,
you are planning to fail.
-Benjamin Franklin
For everything in my life I need some type of schedule, or mock up, or to-do list. I find that I get things done faster and my family doesn't starve. I write everything down from menus for the week, to shopping lists, to cleaning and home school schedules.
The first tip I'm going to give you is an app. Its called AnyList. This app allows you to create many different shopping lists and makes your shopping experience that much easier. You wont "forget to pick something up" or end up with the three of the same thing every other week.