This tip is for Mac users only! The Windows equivalent would be AutoHotKey, which involves scripting.
Keyboard Maestro is an application that lets you create custom shortcuts and macros, far beyond the level of those built-in to apps. It can trigger hotkeys, type text, and even mimic mouse actions. Super powerful.
The most common actions you'll likely want to use are "Insert Text by Typing", "Type a Keystroke", and "Move or Click Mouse".
Keyboard Maestro is $36, you can get it here: Buy Keyboard Maestro