Here are a few of the things that I do when working on an instrument.
I prepare a clean working area where the instrument is clear of debris that can cause damage.
Make sure I have the proper tools need for the type of work I am doing and proper lighting and eye protection.
I would remove all the strings and loose hardware from the instrument and carefully put them in a container till needed. I put all screws and anything that can fall of the instrument and wrap any tailpieces or bridges to avoid scratches
Have a towel or protective material to cover the instrument to avoid scratches or solder from hurting the finish. I would remove a pickguard if at all possible and put the instrument safely in it’s case.
I have a pen and paper to draw the schematic diagram of the circuit before proceeding.
Make sure that you have a “hands off” sign posted to keep others from picking up your work. Everybody wants to pick up a guitar neck when you have it sitting on your bench and parts can drop off it and damage a customers instrument. Make sure you don’t let folks play with your work.