There are many ways to plan your book. You may prepare outlines, plot points, or paragraphical excerpts that you weave together at a later date. Each of these methods is correct, but I have always found that the books that do the best are the ones that the authors allow to write themselves.
Try starting with your opening page and the main character. Then add a simple one sentence list of what absolutely must happen to arrive at the closing page of your book. You have now given the lead to your main character to tell you when to add new characters and subplots.
It takes courage to plan a sketchy outline and then allow your main characters to speak and act for themselves. So while you may be a little squeamish to relinquish the pen just remember that there is only one objective in any book and that is to arrive at the final destination. Try this approach and I am certain that you will find the book to be more authentic and colorful because the characters are simply acting according to their own character.