You know, before my mission, I thought the missionary handbook was a little mysterious. All I knew about it was that it contained the rules that a missionary would live by. If you're feeling the same way, I have some good news for you! The Church has uploaded the Missionary Handbook as a pdf!
This pdf is easy to navigate. If you're currently preparing to serve a mission, I suggest you read over the Missionary Handbook at least once. The standards of missionary conduct and mission rules will obviously be more meaningful to you once you're in the mission field - however, becoming familiar with them before you begin your service will help you to be exactly obedient more quickly.