Complete and utter disassembly

one of the biggest mistakes people make when taking a car apart, is drilling a zillion holes in the panels to separate spot welds. Last thing you want is a panel with holes all over and bent up flanges from separating panels. I have seen way too many rust free panels ruined by novices with drills and chisels. As a bodyman, I like to plan out how and where to separate panels, so there is minimal harm done to the panel that is being saved. Sometime that means using a spot weld cutter from the back side, sometime it means using a small zip disc to carefully grind away the spot welds from the backside. Using a roof skin as an example, if you want to save the skin, drilling through the drip rail flange will result in a lot of holes and damage to the narrow flange of the roof skin. If you do not need any inner panels, then cutting off the roof through the pillars, and taking a lot of care to drill, grind and remove the inner structure is the way to go. It takes a lot of time. The end result is a roof skin with NO holes in the flanges, so it is just like a brand new panel. That way it can be installed just like new with a spot welder, or carefully done plug welds, or panel adhesive if that's your thing. this way you won't have holes that are oversized and ragged like you would have, had you used a spot weld drill to remove it. This applies to many other panels too.
Floors have larger spot welds, that are easier to find, and those are a good choice for using a spot weld cutter, because it saves the frame rail flanges too.
Carefully choosing which method is best, for each situation will result in better panels.