There are two types of shy girls IMO:
Shy girls who are really shy. They don't really open up and usually keep to themselves alot. In this case, gain rapport with her so she'll be comfortable with you. Tone down the C&F a bit and see how she reacts (she usually will be receptive to less C&F than say a wild party girl). Kino can still work with these women. Not too aggressive though. Touch her once or two on the arm or forearm when talking and see how she responds.
Shy girls who need to come out of their shell are the second type. Again, gain rapport, find things in common. This will make her feel able to open up more and get out of her shell. Then she can just "be herself". Again, light kino is almost a no lose proposition. If she responds to it, you're in. If she doesn't respond to it, she won't be totally repulsed by you because it was light and because you've already gotten some sort of rapport going.