The system: five steps, half an hour
011. Check what you already have
Before planning anything, look in the fridge, freezer and cupboards. What's about to go off? What did you forget you bought? Build a meal or two around that first. It's food you've already paid for, and it's what makes a plan cut waste instead of adding to the shop.
022. Pick 4–5 dinners, not 7
This step makes or breaks the habit. Plan four or five dinners and leave the other nights for leftovers, a fridge-raid, a takeaway or eating out. A plan with slack survives a normal week. A rigid seven-day plan breaks the first Tuesday something comes up, and then people drop the whole thing.
Don't pick five involved recipes. Go for a couple of quick 20-minute dinners, one that makes leftovers for lunch, one old reliable you can cook half-asleep, and something new if you fancy it.
033. Write the single shopping list
List everything your chosen meals need, then merge the duplicates. If three recipes use onions, write one line. This is the fiddly bit people get wrong by hand, and it's how you end up with three half-used bunches of coriander.
044. Shop once, to the list
Do one shop against the list instead of several top-up runs. Small trips are where impulse buys and duplicate perishables creep in. Check the list against what you found in step 1 so you don't re-buy what you've got.
055. Stay flexible during the week
Treat the plan as a default you can move. Swap Tuesday's dinner to Thursday when plans change, and cook the quick one on the night you're shattered. A plan you can bend is one you'll keep.