Every guy feels nervous to some extent when he is approaching a woman. Nervous body language is one of the main things that sabotages your approach of a beautiful woman. It is the opposite of communicating that you are confident. And therefore attractive. The biggest issue is not being relaxed and confident in your movements. You move too quickly. Slow down your actions to a quarter of the speed. It will feel ridiculous to you. But to the people watching you will be transformed from someone nervous to someone very confident. Walk slowly. Move your hands slowly. Speak slowly. Slow is equal to confidence. Fast is equal to nervousness.
Think of it like this. When you are doing things slowly you know they are going to succeed. You have no need to do them fast. They will succeed anyway.
The more nervous you feel, the more you should try to slow down what you are doing. That way you will still come across as confident.