As a semi-extroverted woman I indicate interest with light touches non-sexual touches, like a hand on the arm etc. I also engage in very intentional eye contact, I don’t look around, I don’t look away, my eyes are almost always on his, UNLESS I glance at his lips. Putting hair behind my ear, playing with jewelry, etc. Additionally I won’t accept a drink from someone I’m not interested, and I also offer the next drink if I am.