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.
Ctrl+r on bash and zsh (possibly others) for quickly recalling anything you’ve typed before
This is a huge one for me. For those who don’t know, this brings up the rev-i-search utility which allows cycling from most recent to oldest commands executed. It also supports partial finds so if you did ‘cd’ it would cycle the most recent change directory commands.
The forward search (in case you’re somewhere in the history stack) is ctrl+s and operates the same except crawls the command history forwards.
I use these constantly in my normal workflow and they save a ton of time.