Reading Materials - Your First Novel by Ann Rittenberg and Laura Whitcomb Even if you are a seasoned writer/author this book could be very valuable to you in a great many ways, check it out.
Descriptionary - Like a dictionary on steroids! Know what it is but don't know what it's called? This is the book for you. A lot of things in here and what they are actually called, from clothing to medical terms and so on, great resource book.
Other tools: Index cards 5 x 7, for jotting down ideas, also used to plot out your story chronologically.
Smooth writing pens, There is nothing more frustrating than a pen that is rough when writing. They tend to skip and tire the hand much faster. A smooth writing pen is softer as you use it, and causes less stress on the hand and less fatigue.
There you have it, the list is not huge but it is very important.