Rating tracks in iTunes isn’t that easy. In iTunes 12.4, you either click the … button next to a track – in the library, or in the iTunes LCD – and then choose Rating, then a star rating. If a song is selected, you can do this from the new Song menu.
There are third party apps that can make this easier, letting you assign keyboard shortcuts to iTunes star ratings. But OS X also lets you set up keyboard shortcuts for menu items, and I had never thought of trying it with ? symbols. Interestingly, it works.
Here’s what you do. Start in the Keyboard pane of System Preferences. Click Shortcuts, then select App Shortcuts. Click the + button, and, in the dialog that displays, choose iTunes. In the Menu Title field, enter ?. (You can find this in the Character Viewer on OS X; search for “star.” Or just copy it from this article. This character is called, fittingly, Black Star.) In the Keyboard Shortcut field, enter the shortcut you want to use.
Do the same for the other four ratings, from ?? to ?????. Set another shortcut for the menu item None, so you can remove ratings.
In iTunes, you’ll see the shortcuts in the Song > Rating menu, or in the contextual menus:
When you select a track, you’ll be able to rate it quickly using these shortcuts. Unfortunately, this doesn’t work for the currently playing track if it’s not selected. You can, however, press Command-L to go to the currently playing track, then press one of the rating shortcuts.