i haven't altered a book in awhile. i've done just two books and that was awhile ago. i find that preparing a book to be altered is better for the book in the long run, even though sometimes i just want to start collaging the pages right away.
first i rip pages out, and not all of them in the same section of the book. i rip and rip at different places at the book, which leds to a pile of pages on the floor. pages in books tend to be thin especially in fiction books. plus, even though the book may not be very old, i find pages can rip on the edges easily. i like to work on a sturdy surface so i start to glue pages together, and it's usually five pages glued together. i also like reducing the number of pages so the book won't get too fat and start breaking. because my book is a fairly thick novel, it's good to get rid of pages so i won't feel as overwhelmed when i start altering the book.
after i have glued the pages together for sturdier pages, i start to color each two page spread. i like to do this because i don't feel as comfortable working with just the text of the book. i like that the colors give a starting point for my collages. now it's time to start altering!