Mine is using the arrow keys to navigate typed text while writing and editing. It helps speed things up, versus having to move your hand to the mouse to navigate.
Use the Up and Down Arrows to move/jump vertically.
Left and Right Arrows to move/jump horizontally.
Combine Left or Right Arrow with Shift to be able to select text. Use Up or Down Arrow with Shift to quickly select whole/nearly whole sections of text.
Combine Control with Left/Right Arrow to jump whole words to more quickly move to where you want to type.
My main one is to learn shortcuts on your most used programs. Using the mouse for everything is a waste of time, but that has been said multiple times.
My second is to create scripts to do a bunch of repetitive tasks. For example, I have a script I run on my work PC after I log on to the VPN that starts my “always on” programs (like notepad++), unlocks the hosts file, etc. I have some sendto scripts for converting files with pandoc, fetching multiple git repos in one go, etc. It just speeds up things and avoids errors versus me doing them manually.
On Windows I use PowerShell and on Linux I use bash, meaning they work without additional software installed.