I'm not a chick, but I think I can offer a little advice. The most important thing is body language; if you're talking to a girl and she's standing at a comfortable distance from you, not touching or anything, then she's probably not interested in a kiss. However, in this circumstance you can try moving a little closer, maybe touching her hand, and see how she reacts. If you're talking about something more personal than plain friendly chatting and she starts getting closer, chances are you can go for the hand or hug, then for a kiss.
