You can even find published collections of HandyNotes that allow you to keep track of everything. You can type in whatever you want to remember. It allows you to add notes as you go along by an Alt-right click on the world map. HandyNotes works just like you carry a diary or notebook to write notes on any journey but in the World of Warcraft.
Using it will prevent you from missing out on special items. Along with this, it also provides information about the things you are collecting. All the Things is an amazing add-on that identifies everything you are missing such as rare kills, achievements, items, etc, and displays them in an easy to understand interface.