Lets first take a look at your needs and criteria.  What are your goals as far as training your dog?  Since this is such a broad subject, you will want to narrow it down to more a specific area.  Are you looking to for dog training books on house-training, obedience training, leash training? There are also some sub-niches in these categories as well, such as potty-training, or how to teach  your dog to use a pee pad.  So, take a few minutes and jot down some notes on what you want to accomplish in training your dog.  Then you have a much narrower search to look through saving yourself a lot of time and energy. 

Are you training a puppy or an older dog?  This will also determine on the dog training books you are looking for.  There are countless numbers of books for puppies, but for an older dog, you will have less to choose from. 

There are several levels of dog training techniques from the beginner levels on to the advanced level.  What kind of experience do you have in regards to training your dog?  If this is your first time, then you will want to stick with the beginner books, but if you have done this before, you may be ready for the next level of expertise.  And, if this is your first dog, there is a lot of information you will want to have, information that will be left out in the more advanced books.  The more advanced books will have been written under the assumption that the reader already has all the basic knowledge of dog training and will leave out the information that you can really benefit from. 

Do you think you will do better with a book full of text, maybe breaking things into steps but all in written form, or would you do better with pictures showing you the actions you will take with your dog? There are dog training books that go into step by step training with the pictures of your hand commands that go with your verbal commands instead of reading , "hold your hand out, palm up….", which I find more difficult to follow.  If there are visuals to follow, it seems to help reinforce the idea a bit more. 

When you are doing your search for dog training books, you need remember,  what works well for one dog owner, may not work well for you. You also need to realize that not everyone has the same relationship with their dogs nor have the same goals that you have.  When you are able to think about your needs and the needs of your dog, you will be able to find the right book.