My "go-pouch" is a tool holster with a 6"
c-wrench tethered to it, a #2 Phillips screwdriver, a precision screwdriver, a pen, a
matte knife, a
sharpie, and my tactical
LED flashlight.
It's also good to have things like band-aids,
safety pins, pens, pencils, post-its, rubber bands, straight pins,
binder clips, needles, a few spools of thread in different colors, and the like in a separate bag somewhere close to the
stage. Doesn't have to be on you all the time but you never know when a cast member's going to come running off
stage with a wardrobe malfunction and only have a minute or two available before they have to walk right back out on
stage.
Contrary to popular belief, more tools does not make you more useful. Resist the temptation to go out and buy all kinds of gak under the sun unless you see a
clear, immediate need for it. The only thing worse than the guy who doesn't have the tools he needs is the guy who has every tool under the sun but he doesn't have the one he needs in the bag he brought with him that day or the guy who needs 5 minutes every time he goes for a tool because he needs to dig around through 50 tools in his bag to find the one he needs.
You also want don't want to be "Guy who bumps into everything or keeps dropping tools behind him everywhere he goes" because you're trying to fit 15 tools into a 5-tool bag hanging on your hip.
Also don't be "Let me just find a pen" guy. Always have a writing utensil on you. My preference is a fine-tip
sharpie in addition to a chisel tip
sharpie because I can use any of them to write on paper or on
spike/
gaff/
console tape.
Gel pens are okay and I keep them on me, but they absolutely suck for writing on tape.