Buy the book.
For bonus points, buy the book on or after Tuesday, when it is officially in stores. Any copies purchased before the release date don't count against my first week numbers, and those are the numbers that get a person onto the New York Times list. I would like to make the print list. I would have it framed, and then carry a picture of the framed list to show to anyone who says that girls don't like zombies. It would be brilliant. So please, buy the book, and if you can make yourself hold out, buy it once it's actually supposed to be on that shelf.
Write a review.
Amazon, Good Reads, your own personal blog, wherever. Word of mouth counts for a lot, especially during release week, and having reviews reminds people that a thing is worth reviewing, if that makes sense. I'm not saying "only post good reviews," because dude. But any review would be awesome.
Check your local library.
Most library systems allow you to request that they carry books. This is one of them.
Rise up while you can.
We only fail if we're afraid.