How do I compliment a girl's look?

Look at what she chose to show. The jacket in the rooftop photo is a choice. The dog in the hiking photo means something to her. The bread in her bio is something she's proud enough to put in writing. Those are the things worth noticing, because she decided to present them. Compliments that land tend to point at a choice rather than at her face or figure, since she made the choice and can answer it.

Also notice what she didn't put on display. If the photos are all posed and polished, a comment about how relaxed she looks in one of them may feel like you saw past the performance, which is flattering in a different way. If her profile is full of dressed-up shots, a comment about her outfit will probably read as ordinary, so pick something that stands out instead.

There are about three kinds worth using. The first praises a choice: her outfit, her hair, a decision she visibly made. These are easy for her to take because she can say thanks and add a story. The second praises a moment or a setting: the view behind her, the place she was, the feeling in a photo. These invite her to talk about the experience. The third is a light observation about her personality as it shows up in her profile, like noticing the bread and asking what she bakes. That one moves toward conversation fastest.

A draft is the right kind when it names one specific thing, leaves out any judgment about her as a whole, and ends without pressure. It shouldn't mention her body, shouldn't use a word that could be copied onto anyone, and shouldn't ask her to agree she looks good. If you find yourself reaching for the word that sums her up, cut it and name the detail instead.

If you send a compliment as an opener, the best timing is the same as any opener: after you've had a little time to look at her profile and can be specific, usually within a day of matching, and in the evening rather than late at night when a message can read as a come-on. Don't send it in a burst with other messages. One message, one thing noticed.

If she replies warmly, follow the thread she opened, not the compliment itself. If she replies with a short thanks and nothing else, that's an answer. Let it be. Wait a day or two before sending another message, and make the next one about something new rather than repeating the praise. If there's no reply at all, don't send a second compliment. One more message on a different topic after several days is fine. After that, stop. Pressing on the same point is what turns an ordinary compliment into a problem.