Side note: I did not enjoy the tasks in the first location, The Ward, very much and thought about abandoning the game. I'm glad that I did not because the game improves greatly with the next location. So, if you feel the same, stick with it and I think you'll be glad you did.
Basics:
This game offers a very nice tutorial at the beginning. Even if you are very familiar with time management games, I recommend you play through the tutorial to accustom yourself to the gameplay.
Game hints are also available and will walk you through any new features of the game. These hints can be turned off in the settings menu.
The score is calculated by the amount of hearts you earn over the course of the shift. Patients arrive with a certain number of hearts. When you check out a patient, you earn the number of hearts the patient then has. You must work quickly to keep the patients from loosing hearts. "Quick action", "quick assign", and "quick treatment" will cause the patient to gain a heart. The mini games will also gain hearts for the patients. Waiting too long or loosing a mini game will cause a patient to loose a heart.