Make sure you're not keeping too much food as an inventory - go through the freezer, write a list and aim to eat from the freezer until you've got a sensible amount.
If you're shopping weekly, you shouldn't need to keep more than a week's food on hand ( plus a few frozen emergency options). If you have to go through your fridge and throw stuff away before you shop, you're buying too much food.
The final week of the month, aim to avoid shopping altogether and just eat storecupboard meals, eg lentil soup.
When you have something that needs using up, eg chickpeas and an aubergine, google 'chickpea aubergine recipe bbc good food' to bring up all the recipes containing those ingredients. Beware random food blogs though, as their recipes aren't tested, are often disgusting and therefore a complete waste of money.
Look at you're throwing out - stop buying it entirely, whether it's bananas or bagged salad. Any food wasted is money being wasted, and stuff that is left to go off isn't as popular in your family as you think.
Look into keeping basics spares frozen eg bread, milk, to try and stop top up shops as this can mean overspending.
Limit cuisines - keeping the ingredients on hand for thai, Indian, Italian etc can mean a lot of money is just sitting in your cupboards in the form of sauces, spices and oils, which are often not used up in time.
Don't necessarily bother looking for yellow stickers - if you've planned a menu, throwing it out of the window because you've got 20p off a ready meal which will expire the same day is not prudent shopping.