One way you could say it is: "너는 아름다워요." The pronoun "너" is the familiar form of "you," so you can only say this to someone who is a good friend. The verb for "pretty" is "아름답다," and this is how it's conjugated in the polite informal speech level. Same form for "you are pretty." The verb is "예쁘다." "너는 예뻐요." "You are cute," the verb is "귀엽다." "너는 귀여워요." "You are quiet," the verb is "조용하다." "너는 조용해요." "You are shy" is a little different. The adjective for "shy" is "수줍다," but if you say "to be shy" you use "수줍어하다." Therefore, to say "you are shy," you could say: "너는 수줍어해요." I hope this helps!