Libraries and archivalists have long given special treatment to their rarest and most precious books. While most of us won't store all of our books under glass or handle them only with white linen gloves, we can and should make use of some of their techniques for our own collections.

Three common enemies of books are dust, light, and moisture. You can easily protect against all of these with a few precautions, some regular housecleaning, and some special supplies.

1. Keep Em' in the Dark.  Well, not literally. But, do keep books out of direct sunlight and fluorescent light (regular incandescent light is less damaging). Even strong indirect sunlight can yellow and fade dust jackets and book spines fairly quickly.
2. Keep Em' Dry.  Not desert dry, but in general a dry environment is better than a damp one: if you live in a particularly humid climate, consider using a dehumidifier if your normal heating or air conditioning is not keeping your library's air in check.
3. Dust Em'.  If you can't take each book down off of your shelves on a regular basis to clean it - and who can? - you can periodically dust the tops of the books and the shelves themselves.
4. Cover Em'.  This item is very important, especially for all of those first editions and limited, signed, and numbered collector's editions on your shelves. (Whether you bother with this for your trade hardcovers is up to you, but don't forget the rest). Now, I'm referring only to those hardcovers, both old and new, with paper dust jackets. As collectors know, the dust jackets can be more valuable than the books inside them. In any case, they add tremendous value to the books, so you'll want to protect them. Most collectors, including yours truly, use clear acetate covers that protect the jackets from fingerprints, scuffs, tears, dirt and dust, etc., adding years, or even decades, of life to them. I have books in my collection that I covered thirty years ago when they were new, and they still look like they did the day I bought them. There are a number of manufacturers and many styles available. I have always used the fold-on archival covers from Brodart. You can find them online here: http://www.shopbrodart.com/site_pages/bjc/. Whichever brand you choose, just look for styles made from pH neutral, archival materials. And, don't wait to cover a book. When a new book arrives in the mail, I immediately cover the jacket before it ever goes up on the shelf. (I also leave the jacket on the shelf when I read a book).
5. Bag Em'.  If you have mass market paperbacks in your collection that are more than ten years old, and many of us do, you know what time - and repeated readings - can do to them. Typically, the paper becomes yellow and brittle, the covers chip and wear, and their hinges may break and come apart. They can, and often do, become unreadable without falling apart altogether. Now, you may not care with most of such books. However, if you have books that you want to keep, that have become collectible and may still be in good condition, seal them in clear vinyl bags. Comic book collectors have done this for years, and there are special products made just for this purpose. You'll want to look for these, as they will not damage the books that they are supposed to be protecting. Actually, by this point in a paperback book's lifetime, if I have bagged it then I have also decided not to read it again. Instead, if it is a favorite title then I will buy a new reading copy, assuming that one is available. Fortunately, so many older titles are being reprinted these days that this is often easier to do then you might think.