Meal planning saves a lot for us. But I also do a big monthly shop at Costco which is good for some bulk items like nappies etc.
Costco and then prepare in bulk & freeze whatever the baby can have later if not eaten within a day of making. Normally cheaper to buy ½ or ¼ cow upfront and get the butchers to chop it up and package it for you and put that in a chest freezer. Reduce waste age by trying to use every part of vegstable/meat/bones etc. Market places for herbs where you bring your own container and they charge you for the weight of whatever you want.
We meal plan and then I grocery shop to that plan, I'm pretty strict too lol. Eg if we've planned a casserole and need 4 potatoes that's what I buy. I search through catalogues for the best deals on grocery items, usually shop at Coles and have flybuys so use those points if $ is extra tight. Baby markets, op shops and Facebook marketplace for clothing and toys, we are also members at a toy library and use that a lot.