Here are some tools I use at a daily basis at work, I hope these help!
Core temp: https://www.alcpu.com/CoreTemp/
Use this tool to help detect if your processor is overheating or malfunctioning (running at lower clocks / throttling)
Adobe Acrobat cleanup tool: https://www.adobe.com/devnet-docs/acrobatetk/tools/Labs/cleaner.html
Use this tool if you're having problems removing the root folders of Adobe Acrobat / Reader when troubleshooting problems (Don't forget to check %appdata% folders to ensure no cached data is still there!)
Windirstat (Windows Directory Statistics): https://windirstat.net/
Use this tool when trying to get a lay of the land on what is taking up so much space on specific drives without having to manually check top level folder properties to find out what is taking up the space.
This is another tool for checking storage space on a device, however this version is paid, but comes with a bit more power and readability for the average user. Winderstat works perfectly fine as well, so don't feel pressured to use this one!
Notepad++: https://notepad-plus-plus.org/
This program is an absolute MUST for anyone trying to get a more powerful notepad experience, this bad boy is a wonderful tool that I use daily for not only ticket notes while on calls, but even converting data from one type to another on the fly, and even writing basic batch scripts without needing an IDE and not having any text formatting note in the default windows notepad.
Putty: https://www.putty.org/
Use this program to check connectivity and traffic to other networked devices, it can also be used under specific ports to check connectivity with specific sites that authenticate through 443, and even STMP hosts that run through 587 like smtp-mail.outlook.com to ensure firewalls aren't blocking the Microsoft CDNs
Paint.NET: https://www.getpaint.net/
This program is good for more than just photo editing, I've used this program for conversion to very specific file formats like .TIFF and others, a good photo editing program is always a good tool to have around.
This program is a wonderful tool to help troubleshoot some specific issues that might crop up, usually around very obtuse setups and computers experiencing issues with modern authentcation prompts / web app windows and mail autodiscover issues on older machines that used to be networked to an on-prem exchange server. While not a magic bullet by any means it should help you dig to the root of what the problems are.
Samsung Data Magician: https://semiconductor.samsung.com/us/consumer-storage/support/tools/
This tool was created my Samsung to help migrate data cleanly from any drive to a samsung drive, and is a very quick tool to use to transfer data from an old hard drive to a newer SSD, which is a very common occurrence with machines created around 2021 that still for some reason had 2.5 HDD's in them but still had a very set of hardware otherwise.
Profwiz / Transwiz: https://www.forensit.com/downloads.html
This is a wonderful tool for moving windows profiles from machine to machine, or even in a migration project from local -> domain, or domain -> azure for example. This tool pairs well with a portable hard drive since moving data over a network can be unreliable and slow depending on the environment.
MXtoolbox: https://mxtoolbox.com/
This website is a great tool to check email server records, and other pieces like DMARC (Which is really nice, since lots of security is forcing it now to not get filtered)
Ninite: https://ninite.com/
This website allows you to pick and choose applications to install in bulk, and creates a single installer package to run and does a lot of the work for you, great for first time PC setups and profiles.
ShareX: https://getsharex.com/
This program is a very powerful screenshot utility, and is my go to. It allows instant editing of screenshots which is super helpful when creating directions for users to follow, and showing the important parts of screenshots when collaborating or explaining something to users / team members. Just make sure to turn off auto upload and you're off to the races.
ITGlue:
This website is my go to stop for all my documentation needs, and while it's not perfect, it has a ton of power under the hood that can be configured to have dynamic resources updated without input (Certificates, Domain renewals, Licensing, and more).
USB drives: Amazon or Any store that sells compressed air for some reason
These are a MUST for every technician that does any in person work. Here is a small list of things you should always have on USB's, I recommend having at least 10.
Windows 10 32bit bootable
Windows 10 64bit bootable
Windows 11 (Latest version) bootable
Linux Mint / Ubuntu (great for older machines that need a lighter OS)
Clonezilla bootable (for when hardware clones fail!) https://clonezilla.org/
Hirens Bootable: https://www.hirensbootcd.org/ (lightweight temporary windows to troubleshoot problems)
Basic troubleshooting software (portable versions)
Spare USB 1
Spare USB 2
Spare USB 3 (I know, very creative lol)
2. Hard drive cloner / Toaster
A physical device to copy over storage is also very nice for when you can't find software to clone a drive and aren't comfortable around clonezilla yet, this tool is one of those better to have and not need than need and not haves, you'll thank me later lol.
3. 500gb+ Portable hard drive
You never know when you'll need to move over an entire user profile, or a ton of data to backup in an emergency. At least 1 is a must.
4. Ifixit kit
Essentially a one stop shop for everything you might need to open a device aside from a heat gun.
There are a few kits you can start off with, or you can even build your own! below are some links.
https://www.ifixit.com/products/pro-tech-toolkit
https://www.ifixit.com/products/essential-electronics-toolkit
https://www.ifixit.com/products/mako-driver-kit-64-precision-bits
Anything similar to the above links should work no problem!
5. Spare video converters
Not ever user has the same monitor! so video converters are a wonderful tool for troubleshooting.
I recommend having at least 1 VGA adapter for both HDMI and Display Port, and one DVI adapter for both HDMI and Display Port.
6. Ethernet cable + adapter
Any Ethernet cable should work with a reasonable length and a USB adapter for an Ethernet connection for thin laptops that might not have them. The main reason to always keep these around is mainly the fact that sometimes internet drivers just decide to stop existing, or get corrupted after an update. And without access to another device it can be a royal pain getting the drivers and reinstalling them.