I just created a "How-To" over at instructables.com, go over there and check it out! It teaches you how to use the Pen Tool in PhotoShop so that you can get a more precise trace over images than you can with just the Magic Wand. The magic wand is quick and dirty with the emphasis on DIRTY! If you are not too interested in the precision of the trace you need on a given item, Magic Wand will usually work. If you ever need a more precise trace than what the Magic Wand can give you, I highly suggest that you learn the Pen Tool.
The Major advantage of the Pen Tool is that you can trace precisely where you need, and since it uses vectors, it is actually more accurate than a pixel! Technically it could be infinitely more precise than a pixel, but since PhotoShop is a raster based program, that doesn't really matter too much. I find myself reaching for the Pen Tool a lot, maybe too much. It does take time, but there is something relaxing about getting zoomed way in and twisting the vector handles around the various curves to get that pin point precision that only the Pen Tool can offer.
If you are the kind of person that would be interested in learning the Pen Tool in PhotoShop, I am going to guess you are in some way connected to Digital Media. I have recently come across a fairly new organization dedicated to the promotion of the Digital Media fields of work. It is iDMAa (International Digital Media and Arts Association). They have scholarships for students, which would have been nice to know before I got into my senior year, but more importantly, they offer a nice place to network with other people in the industry and even have a section dedicated to helping people find work or people to fill positions. The site is still in its infancy, but save it and keep checking on it, I am sure it will become a very valuable website for people like us in the near future.