Here's some tips that could help. Attempt to fake your confidence. Speak loud and clear, maintain eye contact (don't you dare look at the floor) have good posture, and if sitting, take up as much space as you can without looking retarded. If you believe it, you can control yourself on the outside, even if there's doubt in your mind.
Also, don't begin a conversation unprepared, come up with topics to talk about in order to build rapport (family, interests, jokes, empathy, etc.) Ask questions, but don't interrogate her, don't make it all about you either. Nobody likes that.
Find some common interests along the way and point them out when you do, don't ubruptly bring them up. Internally, I'm a loser and very insecure. Personally, I am very laid-back and very disorganized.
Nevertheless I use these techniques to have a successful conversation most of the time without scaring the other person off and possibly making a new friend. I get bored of people quickly so I don't retain many people I meet in my social circle but maybe you need some more in your life.
