I used to be pretty good about maintaining my tracks' Ratings. But I have lapsed. I used to use my applet Rate Me! Rate Me! to encourage me to rate tracks as they were playing. But I haven't updated that in a few years and, really, it was conceived before Notifications became available.
And while iTunes Notifications are fine, they don't display the Rating for the track. So I had to roll my own.
Rating Notify is a simple applet that runs in the background and when iTunes plays a Music track it dispatches a Notification displaying the track's Name, Artist, Album, Artwork and Rating. The script can also be set to only show Notifications for tracks without a rating. The tracks in these Notifications, for example, have not been rated:
Clicking the Notification reveals the track in iTunes' Music library so you can work on it—or you could use the iTunes Dock menu to rate it (tracks cannot be rated from the Notification, if that's what you were wondering). Additional options can be set via System Preferences: When the alert style in System Preferences > Notifications for the applet is set to "Banners", Notifications will self-dismiss; when set to "Alerts" each Notification will remain posted until it is user-dismissed, as in the screenshot above.
For iTunes 12 and later/OS X 10.10 and later. More information and download is here.