I currently belong to two professional groups the, Music Library Association and the Society for American Archivists. I have been a member of MLA for 4 years and SAA for 1 year. Although I am new to SAA I am already enjoying the benefit of being part of various listservs that discuss issues pertaining to my specific interests. I have yet to explore all the resources available on the SAA website but it is a great resource.
Even before I was a member and before I had enrolled in the MLIS program I utilized the resources on the MLA website. Joining MLA and attending one of their annual conferences was probably one of the best things I could have done to really learn about music librarianship. At the conference I was able to not only attend great sessions and hear wonderful discussions but I was also able to meet the people that will hopefully one day be my colleagues.
Professional groups are great but I have found that just meeting other librarians and having a conversation with them can lead to picking up some of the best information about the library profession. Before I started the MLIS program I really had no idea what I needed to do to start my career as a librarian. I have always been interested in working as a music performance librarian and when I was unsure where to find information I found groups like MLA but I also began searching for professionals that had the job that I thought I wanted to do. I researched contact information and began to contact librarians at various orchestras and performance organizations. Not everyone wrote back but some people answered my questions and provided me with great information.
Even some the people I met at the MLA conference have become valuable sources of information concerning the library profession. I also still sit down now and then with a few members that I consider mentors and pick their brains. It is nice to just sit down have coffee and talk to someone who has worked in your field.