MacOSX provides a lot of shortcut key, if you don’t know yet, please read this post.
In this post, I am going to show you how easily you can create your own shortcut key to use with your favourite application, but this is applicable only for the Menu Item on your Application
1. Remember the Menu item title of your Application. I take Firefox as an example, and I want to create shortcut for the menu item History->Home, so the Menu Item title is "Home"
2. Open System Preferences -> Keyboards
3. Open Keyboard Shortcuts, select Application Shortcuts, then press the Plus (+) button
4. Now select your Application, here I select Firefox
5. Enter the Menu Title & Shortcut for it, then press Add
6. Now test your new shortcut in Firefox