Be thoughtful.
It’s crazy to think about how thoughtfulness can impact someone. Think about how they mentioned a show or book or even color they liked and maybe give them or show them something that you remember they liked. They’ll take that into consideration.
Also, in depth compliments - and I don’t mean “did you fall from heaven” pick up lines etc. if you compliment something on someone no one has before it will stick with them. “The way your eyes squint when you smile is cute.”