I always wanted to paint like the Old Masters. Here are two books that helped me most to understand and use the methods and materials they employed:
"Methods and Materials of Painting of the Great Schools and Masters - Volumes I and II" by Sir Charles Lock Eastlake
This is not an easy read but has great information if you are a serious student of the Old Masters.
"How to Paint Like the Old Masters" by Joseph Sheppard
I found this book to be very useful to me as I began to learn underpainting (grisaille) and have never seen another book like it. Although I consider the illustrations vulgar, I found this to be extremely helpful as a step-by-step guide.
Both books are in paperback and are available from Amazon.