I sometimes teach woodworking to people and I like to babble at them about what I think is the most important tool, especially when the subject is guitar making and the result has to be very good. The tool is light. In 1858, using just light, Léon Foucault could measure the surface of a polished telescope mirror with an accuracy of about a millionth of an inch. It’s a powerful tool.
Good shop lighting of course, plenty of it, and of a color that’s natural and diffused so it doesn’t cast obvious shadows. I like a mix of halogen and fluorescent.
For carving, or flattening surfaces, a strong point source is great. Sunlight is best. Here’s afternoon sunlight showing high and low spots and the smoothness of the curve on a neck.
If you’re older than about 5, magnifying goggles are useful too.