First I added a 1" border all the way around the picture, straightened, cropped, then resized to original size.
Converted your picture to B/W using Russell Browns "Film-Filter" method as shown
here (it is a movie and may be a long download.. be patient please).
I adjusted the red and yellow channels till they both showed as white as possible using all three sliders.
Used "Neat Image" found
here at the default "Muddy looking Image"to remove a little noise.
Followed this
Tutorial to clean up image.. (lots of cloning and healing toward the end)
Using this procedure should get you started on your way to wards coloring.. Get a GOOD image first before you start painting
~~Original~~cleaned a bit~~Sepia~~