Never touch negatives, Fingerprints leave salt, which will enntually bleach the negative. It is best to store your negatives using a catalog system so they are easier to find when needed. You can store by year or family name. To do this just take a picture of a blank piece of paper. You may also store your negatives in three-ring books.
Photographic stores carry special three-ring negative sleeves.
Make sure they are archival sleeves. It is also a good idea to sotore negatives and orginals in a safety deposit box and only disply your copies. Go through your old negatives and make sure they are properly stored and check if they look like they are breaking down. The negative will look thin and does not have a sharp image. If it is an important image make another negative just to make sure.