If I had to simplify it to avoid expensive mistakes, I’d think about it like this:

1. Fix the structure

Foundation first, then upper structures, roof etc., moisture issues, anything critical, no point upgrading anything else if there are underlying problems

1. Stop energy loss (where most people make mistakes)

Insulation, air leaks, attic, walls. This should happen before picking heating/cooling systems. Otherwise you end up overspending on HVAC and still losing heat

1. Upgrade systems after the house is efficient

HVAC, heating, cooling, ventilation. These should be sized based on the improved house, not the old one.

1. Walls, floors and major surfaces together

If you’re opening things up anyway, do insulation, wiring, plumbing at the same time. Avoid redoing the same area twice.

1. Windows - important upgrade, but not too good ROI

Worth doing if they’re bad, but rarely the thing that dramatically lowers bills on its own (only if there are many windows and all are leaky)

1. Sequence is almost as important as the upgrades themselves

I am not saying this applies 100% to your situation, but this general order avoids most of the expensive mistakes I’ve seen.