To add to the good advice you’ve already been given… say the compliment and then let it go. Move on, change topic, whatever. The worst is when guys (or anyone) gives me a compliment and expects that to be an “opening” to a dialogue or flirting. If someone says a compliment (even if slightly awkward), but then genuinely moves on and just lets the compliment land on its own, that’s a pretty good indicator that’s all it was.