I regularly work with individuals and organizations to assess, organize and catalog their archives, as well as advise them on what steps to consider next. As an individual, you may be working with your own archive (what we call "personal papers" in the profession), or you may be trying to figure out what to do with the papers of a loved one who has passed away. In some cases, you may have materials relating to an important or famous person that comprise a smaller part of your own papers, or have a significant collection that you've created (like fanzines, flyers, or artists books). If you are an organization, your archives have grown naturally in the course of business, and you may simply have reached critical mass in terms of storage capacity.
Once you've got a good sense of what you have, how do you decide what to do with your archive or collection? In some cases, you may be able to sell your personal papers or organization's archive to a research institution. This all depends on finding an institution that has a healthy acquisitions budget, and that actively collects materials related to your archive. I can assist artists, writers, performers, arts organizations, and collectors place their archives with suitable institutions (or, in some cases, with private collectors). Academic libraries, special collections, and research institutions are interested in creating research-rich collections that support scholarship in their specific collecting areas. Don't assume you have to be super famous to sell your archive -- it's all about fit, and budgets!
That said, many institutions cannot afford to buy archives, especially in light of the costs of preserving them and making them accessible. In this case, you may want to consider a donation. The Society of American Archivists has a nice guide to donating your archive. If you are donating materials not created by you, you may qualify for a charitable donation deduction on your taxes. Unfortunately, artists, writers, etc. cannot legally take a deduction on their own archives. If you are donating a collection of materials created by someone else, or someone else's archive, you may qualify for a charitable deduction. I am not an accountant, so please contact a professional to figure out how your donation or sale might affect your tax situation. I am a USPAP certified appraiser, however, and am qualified to do IRS appraisals of archives if you do qualify.
It's possible you may not be ready to part with your materials. If you still regularly access the archive for your work (be it business or creative, or both), you may want to plan for the archive's future disposition. The Joan Mitchell Foundation's Creating a Living Legacy initiative has good information on Estate Planning for artists, and an in-depth resource on artist-endowed foundations is available from the Aspen Institute. For artists, documenting and cataloging both your work and your archive are important components of planning for the future.