What tools are essential/desirable/wishful?

[Rick]

I am sure we've all experienced a guitar that is not set up properly, or has other minor imperfections (e.g., improper nut), and makes it play awful or sound terrible.

Which tools do you think are essential? I think that doing intonation & neck relief is, hands down, the most important. I therefore keep a toolbox of basic goodies from Stew Mac (lengthy straight edge, measurement tools, fret tools, truss bar tools, etc).

Desirable? Working on the nut, or bridge, or working on the electronics.

Wishful? Anything that deals with the structure, or finish, of a guitar is scary for me. I'd like to learn, but sanding down the finish on one of my Rics "just to see what happens" ... uh, no thanks. I'd need adult supervision.

Any real-life techs out there that can give us pointers as to what we should all have in a basic tool kit to keep our Rics performing perfectly? And maybe what our next step should be?