Leather is beautiful but it requires care. In our climate a leather bound book should be reoiled every 2-4 years, but only with oils made for rare books. Read about the proper way to first buffer the leather to help it resist acid deterioration and follow with the oiling. Photographs are very fragile. Most color dyes will have color shifts within 20 years.
Slides fade and are liable to fingerprints.
The newer resin coated print papers are very sensitive to deterioration from ultraviolet light and should be stored in the dark whenever possible. Most film and print processing is not done to archival standards, causing deterioration of one sort or another over a period of years. The best is to read as much as possible in this field, but avoid the advertising. Even Kodak has been slow to let the public know about these things. Always make a copy of a glass negative before doing anything with it in case the glass breaks.