The Problem: inefficiency, methane, high carbon footprint
The Solution: buy what you need, good storage, compost
Make a rough meal plan for the week before going shopping and buy only what you will eat
Eat or freeze leftovers
Get a compost bin from the council and follow their guidelines, stirring it regularly. Give compost to someone with an allotment or your own garden.
Look up how to store different fruits and vegetables for maximum life span in your fridge. For example, spring onions and celery can be stood in a glass of water for maximum lifespan. Similarly, carrots can be floated in water while potatoes and apples should be stored together in the dark.