Charlotte is supposed to be one of the most beautiful women in the world and I was worried that if she wasn't genuinely beautiful then people wouldn't buy into the story. So I spent a lot of time trying to make her as attractive as I possibly could and used photographic reference to this end.
Her face is mainly inspired by Kate Beckinsale, and maybe Alessandra Ambrosio, and her body by supermodels such as Gisele Bundchen and Josephine Skriver. But, this is fiction so Charlotte's breasts are relatively large for a supermodel.
With the other love interests I was focused more on making them distinct and characterful, and less on trying to make them objectively beautiful.