I always liked to study for the written tests with the Gleim books (red covers). They are easily found online at pilot stores like Sporty's. I felt that of all the manulas they were the best. I actually ended up buying all of mine in advance and then had duplicates when ATP sent me the infamous box. If you find that just the books are not enough then I recommend the videos by King Schools. The Kings (
www.kingschools.com)teach the information in a way that keeps it informative, yet interesting. I sold the extras on eBay and made a portion of the money back.
Chris