There are a bunch of little snippets I occasionally need but can’t always quite remember the syntax for, e.g.
*  for checklists
``` for code blocks```
To use these without looking up the syntax, I’ve configured shortcodes for more memorable commands –
* t for checklists and
´´´ to paste the current clipboard into a markdown codeblock.
I’ve also configured
!!alt for ⌥ and equivalent commands for all the other common macOS symbols, nicer → arrows ← etc.
There are a bunch of other ways to do this – you can get a lot done with the built-in macOS / iOS text replacement options, or a lot of other tools also offer similar replacement options – Alfred.app is my go to workflow tool of choice.
So if you have anything you find yourself struggling to remember or would like nicer symbols, try setting up some handy text replacements!