Personal archives include material of long term value to you.
They can be in many different formats (photos, word documents, pdfs, video, scrapbooks, and more).
Preserving materials successfully takes a little time and thought.
Toss what you're sure don't want to keep and focus on what you DO want to keep.
Quick tips by format (analog and digital) from the American Library Association: http://www.ala.org/alcts/confevents/preswk/quick-tips
Digital preservation tips from the Library of Congress: http://www.digitalpreservation.gov/personalarchiving/