* Pick a supermarket and stick to it, get their loyalty card thing if they have one
* Go once a week on roughly the same day
* Don't go on an empty stomach
* Know what you've already got available
* Figure out how many meals you need for the week, and only buy what you need
* Take a basket, not a trolley
* Keep ready meals to a minimum (they tend to be full of bad shit and are expensive)
* Get fruit for snacks (cheaper, healthier)
* Buy stuff for lunches, so you don't have to buy lunches during the week that work out to be a lot more expensive