I usualy buy food that I know will last me a while like rice, beans, lentils. When it comes to fruits for milkshake, I wash them and put them in the freezer, so they won't go bad. Great for a healthy Spring and Summer smoothie!
Things I do with food I may not eat:
1) Scraps like Banana peels and egg shells, I blend them and put them on soil. Plants love it!
2) Give food to my friend!
3) Revive stale bread with a bowl of water and microwaving it next to the stale bread.
4) Stick to my grocery shopping list...
I try to save as much as I can and save money for rent or other things that may need to be paid.