How do you create a character with preferences? What does that mean? It means that your character is realistic and connectable.
A character with preferences is one that has character. Sounds odd that way, but that is exactly what I mean. Your character has favorite ice cream flavors, favorite types of food, and things they hate. What makes them stand out?
Think of it this way. Have you ever watched NCIS? What are the characters favorite foods, drinks, movies, hobbies, etc.? These characters are consistent, unique, and identifiable. That is what you want with your characters.
As you develop your characters, decide what preferences your characters will have. Think of what makes them stand out. Do they have to have a special coffee? Do they have a special kind of food they are always eating or a chewing gum they are seen with? What kind of preferences does your character have?