Gently remove the cover if it is falling off the rest of the book. Apply acid-free glue up and down the book's spine, and carefully place the cover back on the book. Allow to dry before continuing with repairs.
Use clear bookbinding tape on the inside of the book cover, front and back, to repair a cover that is torn or crumbling. Place each piece of tape next to one another, using as much tape as needed. Use extra tape around the inside edges of the cover if necessary, as this is where many paperback covers sustain the most damage.
Carefully remove any blank pages in the front or back that are too ripped to repair.
Apply bookbinding tape to any pages in the front or back of the book that can be repaired for additional reinforcement.
Repair pages that are falling out by carefully lifting the page and applying a thin layer of glue to the inner spine. Gently place the page back among the other pages and allow to dry before making similar repairs.