Using her name implies that she’s worth your time and worth knowing.
You could also try something like, “That necklace is beautiful” or, “Those pants look really good on you. ”
Say something like, “You look like Rihanna!” or, “That looks just like something Rihanna would wear. ”
“That dress is beautiful. The color really brings out your eyes. ” “I love that blue sweater on you. It really makes your eyes pop. ”
If she has a streetwear vibe, you might say, “You always look so laid-back and cool. ” If she’s more of a business casual type person, you could say, “Your style is so sophisticated. ”
Try something like, “Wow, I love those shoes! Where’d you get them?”
Just stay away from anything like, “Wow, you’re so brave to wear that in public!” That’s not really a compliment, and you might offend your girlfriend.
If she asks you about something in particular, you can be honest, but you don’t have to be rude. Say something like, “I’m glad that you like that skirt! It’s not my absolute favorite, but if you like it, that’s all that matters. ”
Even when you have good intentions, pointing out someone’s body can make them feel uncomfortable.