夸赞别人好看时，可以使用以下几种英语表达：
You're so beautiful.
You're gorgeous.
You're pretty.
You're charming.
You take my breath away.
You're drop-dead gorgeous.
You're easy on the eyes.
You're attractive.
I love your features.
You have such a beautiful face.
You're very attractive.
That's a nice coat.
What a lovely dress.
I like your jacket.
Your hair looks great.
根据具体的场合和对方的个性，可以选择合适的表达方式来夸赞对方。例如，在正式场合可以使用“You're so beautiful.”或“You're charming.”，在非正式场合可以使用“You look great today.”或“You're drop-dead gorgeous.”。同时，注意不要过度夸赞，以免让对方感到不自在。