Not much at all, but I have time on my hands these days and shop for what I need every couple of days.
I plan my meals around what I have left in the fridge first and foremost, and tweak recipies to use things up. Eg this week I had a lone pepper, a couple of mushrooms and half a bag of spinach, so I made bolognaise and chucked the lot in. Often I make soup to use things up. I put leftovers in the freezer for an easy meal another time.
I use fresh produce in the order it will go off. E.g. if there are strawberries and blueberries in the fridge, I'd use the strawberries first. A slightly brown banana or an apple, I'd use the banana, regardless if I'd prefer the apple!
I'm also not that worried about dates. An out of date egg, cheese, yogurt would be used. I'm more careful with meat, but a day or two if it looks and smells OK, I'd still use it. Never fish, but I'd buy that on the day I plan to use it.