Not an expert at doing ahead, but one thing I do is double the amount of bacon I would need. And freeze the remaining. I bake the bacon and not fry it, so cooking more is easier than on top of the stove. I also cook more ground beef than I need and freeze, you can take it out and use for a lot of recipes. I freeze leftover gravy, too. It freezes well.
Another thing if I have too many mashed potaotes, mix up my leftovers with an egg, sour cream, shredded cheese, ontions and freeze it for a side to a future meal. Just a few ideas.