Keyboards shortcuts for hidden characters

Use Option & Shift keys to access hidden characters in OS X

For even more hidden characters and emojis, use the Fonts panel and click on Action (gear) > Characters... or press 'Ctrl-Command-Space' to reveal Character Viewer.

Select a category from the side panel

Select and then Add to Favorites

You can access even more categories by clicking on Action (Gear) > Customize List...

Use this in conjuction with 'Text Replacement' to automatically replace characters.