For store remodels or large reset work:
I use a stepstool which is also a tool box. ( I'm vertically challenged)
Multi tip screwdriver ( I do lots of battery replacements and interactive installs)
Small hammer ( for those shelf brackets that have been in place for years)
Pliers ( some of those price label tracks just won't give up the ghost, also wing nuts that won't budge)
small tape measure ( for back rooms where the shelves and brackets are not separated, also for setting shelf heights)
Painters tape, packing tape, index cards ( to set where the shelves are supposed to go for other people, cards to label defective, damaged, etc. product, clear tape to seal boxes if you have to send back product)
Magnifier ( those nail polish bottles and mascara tube numbers are just too small)
Garden type kneeling pad ( It helps if you are doing bottom shelf work, I have seem guys using the workman type knee protectors)
Outlet tester ( sometimes you need to know if the interactive display is broken, or, if the outlet is dead)
Various colored markers, pens, pencils
Snug fitting plastic gloves for dusty work, work gloves for the really ugly stuff.
Plastic hangers for hanging damaged packaging (product is still good, just has a torn hole to place it on hook)
Small Swiffer for dusting.
All my stuff is well marked or brightly painted. So many people show up without anything for resets. They like my tools so well, they try to liberate them occasionally.
I do keep a first aid kit in my car with all the Aleve, triple antibiotic cream, band aids, ace bandages, etc.
I also have extra dividers, label holders, hooks, etc. in my car. If I need them, I go get them.
For cycle work I travel very light- clipboard with storage, 2 pens, paperwork and a note pad.
If I don't think I will need it in a store, I don't drag it along.