Being shy was one of the things I was most worried about too - I got over it (somewhat, at least) by volunteering at a hospital. What I do there doesn't really have anything to do with nursing, but just getting comfortable in a hospital setting helps out - and I also learned that while some patients can be in a bad mood, they're not monsters. Some patients have mentioned to me that their nurses are shy, but it seems to me that these nurses are the ones that the patients relate to the most, so they appreciate them a lot.