Don’t overbuy, your appetite is going to decrease. You won’t need as many groceries as you used to and nothing wastes grocery money worse than throwing food in the trash.
I always buy store brand when possible (unless I’ve found a particular item to be undesirable, normally there is no distinguishable difference between store brand and national brand)
I browse the meat section for steeply discounted, soon to go out of date packages. I then cook them up immediately and freeze excess.
Buy the bulk “family packs” meat packages and divide into individual portions and freeze.
Use stems and peelings from your produce to throw in with your bone stock. You can throw them in a container and freeze until your next batch of stock. You can also use produce that is about to go “bad” for this.