1. Wash your hands, and wear gloves. Do it in a dust free area. Do not move the flashlight when doing the mod. Keep pets out of the area.
Clean the area with a vaccuum cleaner, and wait for the dust to settle. Try to do the mod moving as little as possible.
DO NOT TOUCH THE REFLECTOR.
2. Use a blower from the reflector opening, or a can of sprayed air. Blower is better since it’s reusable.
3. Same tactics as number 1, but they are doing it in a clean room, hopefully. Not as extreme as semi conductor manufacturing, but way better than most homes.