TL;DR: Arrive early to get the marked down meat/fish (and bread) which expires the next day. Freeze the extra.

I’m not organised enough for this and don’t eat these things but hopefully this is useful.

Another tip is to learn the day your local supermarket restocks and shop right before closing the night before. A lot of items will be on clearance.

One bakery used to have a discounted table of day old bread but that was a long time ago and I don’t really see that anymore.

If you don’t drive (and especially while PT is free) buy a wheeled shopping cart from a local $2 shop. You won’t regret this. Some of them are foil lined to help keep items cool as well.