I would like to start by saying that it is likely you would need a graduate degree to be fully immersed in this field. However, as far as your undergraduate is concerned, anthropology, is not the only choice. An undergraduate degree in biology, chemistry, math, or another science can also provide good preparation. Once you have your bachelor's degree, you can take some time to consider what type of graduate degree would work for you. Try to look for a mentor, and possibly join a professional organization such as the Society of Forensic Anthropologists (SOFA). This organization helps forensic anthropologists network and stay current on what their profession is all about.
You may also want to consider post-graduate certification. Take a look at what the American Board of Forensic Anthropologists (ABFA) offers.