Lots of good advice, suprisingly enough once you reach the conversational stage, your subconcious will do some of the work for you, here are a few indicators, that a woman is interested in a man...

while in conversation,

Reapeated touches own hair

Touches the man, ususally very delicately and frequently , on the arm, shoulder etc

When seated, faces the man directly throughout the conversation. If the woman sits at an angle during the convo, she is looking to leave and has lost interest.

Repeated leg crossing.

another thing, ask him a lot of questions about his life, nothing too personal, but about say his hobbies, his friends, what he does at the company, men like to feel important and at the center of attention