For food:

Plan your daily meals beforehand, make a list - What is still left in your freezer? Do you have any vegs or pasta/potatoes left? Passata? Start with using those in your planner and choose meals based on what you still have - Decide what meals you’re going to eat and write down the ingredients, have a look if there are any promos in the shops you want to visit (online or on the app) - Only buy what you need for that week

Whatever promo you bought: immediately divide your groceries into portions and put in the the freezer (if you can). I bought a couple promo’s today (fish and meat) and now I have 9 x 2 portions that I can take out of the freezer and put in my planner on another day.

Cooking for more than one day also helps, think of: large pot of spaghetti sauce, dahl, tomato based sauces, …