Here's a couple pictures from when I was insulating and air sealing the sidewalls of one of my rooms upstairs.
I had to pull up the side attic floors. Sealed about 60 feet of floor cavities that were open to the side attics, and stapled about as many feet of r-13 over the wall insulation (which wasn't making good contact with the walls). Also insulated the garage ceiling and the foam sealing panels to try to keep the floor cavity insulated. Also had to reroute a bunch of wires to get them off the side attic floors. Also sealed the doors to the side attics, insulated them, rewired some outlets. Air sealed all the outlet boxes and the like. And that's just what I did in the side attics. Did it all early in the summer too, a few hours at a time in the evenings. Miserable work.