The first thing you need is a book. I prefer smaller, thin books because it seems more personal to me. A larger book can be a daunting thing. Do not feel like you have to alter every spread that you leave open in your book. It can be an ongoing process that you come back to. You might invite an art friend to do a spread for you.
It can be a board book or a hard covered book. You might even want to alter a journal. I don't recommend altering a spiral bound journal unless you don't mind the pages coming off the spiral binding. I just did an altered board book on my blog. Look further down in the posts to see what I did. I am choosing a hard cover book for this ongoing tutorial. I actually went and got a couple from skybluepink. I wanted to have some fun altering this book. I also wanted to show Dremel what a shaped book looks like. Yes, they said they could do this on their scroll saw. I will see about that this Friday.
I am not sure what the shape is of the bottom book. I also got a shorty book that I will alter. Maybe that will be for favorite words or I might play with some letters or stencils for the shorty book. I got the cut books from skybluepink.com. She also sent me some very fun stuff that I am going to use in my AB spreads. I will show them to you as I use them. You can find the books here: http://skybluepink.com/alterables2.html. I figure that I might as well go for funky when I am doing the AB stuff here. You can even use the shaped books for an AB art doll. I have seen it done and it is wayyy cool.
You can get hard cover books from bargain bins, used bookstores, library sales, your dusty bookshelf. Don't tell my kids but I used to raid their bookshelves for a hardcover or board book when I was really itching to alter something. I don't do that anymore. They are getting older and too smart for that.