Something I picked up a long time ago which has always helped me. When you have eye contact with a girl, preferably at not too close a distance (but still effective) switch focus back and forth between her left and right eye, maybe while smiling. It will create a 'twinkle' in your eye from shimmering light reflection. Some subconscious shit that works on girls. And I guess this is best if your talking to a girl, then while speaking you get eye contact, smile aswell, (helps if you're saying something witty) and alternate focus between eyes.