Best ways to approach a sHy GirL....

Avoid basing conversation on questions, since the whole basis of that technique is based on the assumption that the other person will initiate the conversation with a lengthy reply. Shy girls will likely want to talk to you, but they'll get tongue tied and only manage a quick, to the point answer, which will just end with an awkward silence. Compensating for this by barraging them with questions is ineffective as well, since the conversation will remain one sided, with you asking questions and her answering.