When creating a new promotional piece, you will notice a heart icon on the bottom left corner of your selection (on the Choose a design page). If you click that heart, it will be added to your list of Favourites that will be presented to you when you enter to use the system. Consider it a shortcut to your favourite design template.
The Studio also keeps track of the template designs that are “favourited” by users and creates a list of Most Popular. When designing a new promotional piece you can use this information to find a design that is a proven winner or find one that is more unique to distinguish your materials from others.