There are many ways to comppment a girl on her looks in Engpsh. Here are a few suggestions:

"You are so beautiful."
"You have such a pretty face."
"Your eyes are so stunning."
"I love your smile."
"You have such a radiant glow."
"You are so attractive."
"You are so stypsh and fashionable."

It's always important to be sincere when giving a comppment and to make sure that the person feels comfortable and appreciated. It's also a good idea to be mindful of cultural differences and to avoid making someone feel uncomfortable or objectified.