There are a lot of books available on the Law of Attraction, and many of them are really good. They all explain the Law of Attraction from different perspectives, including the scientific perspective.
This is important because, in order to make this "law" work in your life, you need to understand that it is a scientific principle, like gravity. If you properly apply this principle in your life, it will help you get what you want.
I don't believe, though, that understanding this principle is enough. You have to actually apply the principle in your life. In other words, you have to take action.
This is how Jack Canfield's Key To Living The Law of Attraction will help you. Instead of just another book explaining how the law of attraction, this book offers you exercises to help you determine what it is you really want out of life. (These principles can be summed up in the following three words, which is your action plan: clarity, purpose, and action.)
You start by doing the exercises that helps you determine what your purpose in life is. If you really want to understand why you're here, and what you were meant to do, you have to do these exercises. This proccess also includes determining what your passions are. This can be anything from wanting to help children to helping any other specific group in society.
Once you've answered these questions, you'll use this to formulate your purpose statement. Then you define your dreams and goals. You'll look at seven key areas in your life: personal, relationships, health and body, careers and education, recreation, financial, and contribution (Your contribution has to do with what you ultimately want to do with your life.)
The next steps you take are to write your goals list, as well as affirmations that will help you reinforce what you want and get this information grounded in your subconscious. Finally, there are other exercises like meditation and prayer that are meant to reinforce your vision and keep you on track to attain it.