Use a photocopier when you want to keep something from a library book or magazine. Torn out pages take time and money to replace, and the binding of the book is weakened by page loss. Often more pages are loosened and will fall out soon. Keep food and drink away from books. This includes water and coffee cups.
Books are easily soiled and food residue attracts vermin.
Keep books dry in wet weather. Have a plastic bag available. Don't read library books in the bathtub. Wet books quickly become mildewed. Mildew spreads through books like the plague and presents a serious health risk to some people.