Well, usually in manga, to become a princess, you need to have kindness, courage, and a heart full of love. Also, a bit of luck and some magical elements might help.
Often, in manga, one becomes a princess by having a unique destiny or by showing extraordinary qualities like bravery, compassion, or intelligence that make her worthy of the title. It could also be a case of a mysterious prophecy coming true.
Well, there are several common ways. Sometimes it's because of a prophecy or a hidden bloodline. Or it could be that you performed a heroic act and were rewarded with the title of princess. Another possibility is that you were chosen by a magical force or a wise ruler.
You need to start with basic sketches of the figure, focusing on proportions. Pay attention to the details of the face, like the eyes and hair. Practice different poses and expressions for a more charming princess.
In the end of Kiss Me Princess manga, there's a big twist. The heroine discovers a hidden truth that changes everything and leads to a fulfilling conclusion for all.