I use Cmd-S to get the focus to the Keyboard Maestro search field.
This is a shortcut internal to Keyboard Maestro as opposed to
shortcuts defined by the user.
There must be many other useful internal shortcuts, some documentation and maybe a cheat sheet somewhere but I was unable to find them.
Edit: I found many interesting ones thru the menu bar. Maybe enough to get going.
Thx
You could check out KeyCue. It's sole purpose is to quickly show all keyboard shortcuts; both application specific ones as well as system shortcuts.
That's the traditional method of discovering keyboard shortcuts.
Don't forget to press various command-key combinations as you look through menus – they will sometimes alter what menu items do, and the associated keyboard shortcut.
@cdthomer's thought about KeyCue is a good one. Although it's a commercial utility and not cheap, 19.99€ is reasonable for the functionality it provides. (It's helped keep me from pulling my hair out for well over a decade now.)
For a less capable freebie look at CheatSheet.