I have those and also a belt shortening clip (I doubt I'll ever use it but if I need one I have one; it was free), a knife, duct tape (for putting pool noodles into pyramids), a note pad for giving parents websites, lists of seats to look at, names of stores, tether anchor part nos., etc., a clipboard, a large doll that I use for demoing w/ expectant parents, recieving blankets ditto, zip ties (for tying up dangly tether straps-- could use rubber bands but out here I find they get hot, shrivel and fall off), TB screws and a mini screwdriver, a stapler for stapling my waivers and check forms together, an alphabetical accordion file where I keep my completed paperwork filed by driver's name and date, my notebook where I keep my paperwork (which includes my liability waivers, check forms, and other forms like the report a defect form that parents might need as well as some quick reference lists like handle positions for different infant carriers, HWH and HWRF seats available, oh, and a kind of phone directory of techs/Instructors I know whose numbers aren't stored in my phone so I can call them if needed, among other things) and also a measuring tape and scale (for weighing and measuring kids when necessary, though I usually only use those at bigger check events.) I know some techs bring a laptop and a CD of manufacturer's instructions and things like that but I don't have a laptop so not I. If I have a tricky question and no instructions I call someone. Usually Judi if the manufacturer is closed.
Oh, and extra flyers and business cards to give out so people can more easily spread the word.
I have a backpack I keep it all in except for the baby doll and the scale (the scale fits if I have to but it makes it kinda tight, and the airline broke one when I checked my kit. So now I just mostly don't keep it in there, I grab it when I'll want it.
I'm sure I
could make do with less but I've used everything I've got more than once. (Except the form for airbag on/off switch. Never given one of those out. And the BSC. Haven't used-used it but have shown it to other techs.) So I like having it around.
The paperwork was the most time-consuming and expensive part to get together. When you've done a few checks you'll get a feel for what you like in a checklist, and you can decide whether to make your own or use one that's already pre-prepared. (I use the St. John's Hospital one from the back of the tech manual, with my own liability disclaimer subbed in.)
I've found one thing that's important, since I'm quite often recommending new seats for people with expired and/or outgrown ones, is to be aware of what is out there and especially what's available locally, where, and for what price. I don't think I have ever given a parent just one choice and said, "This is the best one for you" though I think I can conceive of a situation where only one seat might work. I can tell them what choice I would personally probably make were it my kid in my car but I try to give them at least 2-3 appropriate choices and preferably more, and make sure at least 1-2 are available in store locally. So I do lots of field trips to not only play with new seats but be aware of what each store is carrying and for how much. I know most parents want to be able to touch and see a seat before they buy it so I have to know where is the best place to send them to do that, given how much they want to spend, etc. That's something you can start doing now, with the added bonus that you can start to make friends with the proprietors of any local baby stores so once you're a tech you can say, "Hey, give people my number if they have questions!"