The correct size allen wrenches for the truss rods, bridge saddes, etc. on your guitars is essential. Some people measure the neck relief, which is fine, but I usually eyeball it from the nut to the bridge, get it straight, and raise/lower the bridge to suit me.
I've done it for so long I don't even think about it. You probably should check the neck relief w/ a straightedge for awhile until you find what you prefer.....some like a pretty healthy bow, not me.
If you run into intonation problems you'll likely want a good tuner to sort that out.
Screwdrivers of the right size and proper type are essential also. It sucks to ruin a screwhead on your guitar because that screwdriver you had laying around "almost" fit snugly!
Guitars
Wilburn Versatare, '52 FrankenTele(Fender licensed parts), Fender USA Roadhouse Strat, Fender USA Standard B-bender Telecaster, Agile AL 3000 w/ WCR pickups, Ibanez MIJ V300 Acoustic, Squier Precision Bass,
Amps
Ceriatone Overtone Special, Musicman 212 Sixty-Five, Fender Blues Jr., Peavey Classic 30, Fender Super Reverb, Traynor YCV-40 WR Anniversary w/ matching 1x12 ext. cab, Epiphone SoCal 50w head w/ matching 4x12 cab (Lady Luck speakers), Avatar 2x12 semi-open back cab w/ Celestion speakers
Pedals
Digitech Bad Monkey, Digitech Jamman, DVM's ZYS, Goodrich volume pedal