As a former archaeology student I know that the subject is as difficult as it is enticing. It demands a lot of reading and research, and a high level of understanding. But as with any subject, if you work hard at it, you can succeed. Renfrew and Bahn's "Archaeology:Theories, Methods and Practice" is an essential book to own for anyone in the field.......from students to lecturers, up to fieldworkers. As the top book on a University reading list for Archaeology, you will find everything you need to know in here. Do be careful, however, as this book has been written to accomodate all areas of an entire degree course, and does not specialise. If you are taking particular fields or interested in specialist archaeology i.e. underwater or Egyptology, I suggest a search under those respective titles on this website AND Amazon.COM, as many good publications on the subject come from the United States.
Buy this book for study or for hobby, it is well set out and has lots of interesting facts about past societies, archaeoogical techniques, and the history of the subject. Use it as the base for any query or study within the field, and you will not be disappointed.