Check the ground first to see how bad it is. Uneven spots make loads tilt and things can fall over easy. You end up moving the weight around a lot just to keep it steady. It takes slow, careful work to get everything sitting right. I often use scrap wood pieces to prop up wobbly corners, but that adds more steps. Really, the key is accepting it will be slow and fussy.

Ever think we overthink what counts as a real mistake?

My 1987 ranch house had one room that stayed 15 degrees hotter until I messed with the register dampers. Sure, @kimc49, "balancing airflow" is the nice term for it. I called it a two hour swear fest where I crawled around guessing which vent to close. Felt like a wizard when the temperature actually evened out, though. Old houses just want to fight you.