Hint...I figured this dilemma out when I was in my 20's. What I would do is think about my conversation with her and then write down a few bullet points to speak about before I called so the conversation would never lag. Also, when making a date give a girl options rather than ask a question. "Would you like to do this or this?" Not..."Do you want to go out sometime?"
This goes back to my sales training. Never ask an open ended question that allows for a No answer. Planning ahead makes you seem confident even if you're not. Also, most people prefer to talk about themselves so ask specific questions that allow you to find out whether you really like her or not. She will think you are caring and a good listener.
My next course will address how to put forth the issue of physical intimacy without being forward, or making her feel uncomfortable. But you have to
for that one