also look at MV's leather tutorials on massivevoodoo.blogspot.com
and Painting Buddha's youtube channel (no idea which is the best for leather, but the last 2 from the shieldmaiden was leather painting)
They recommend a light brown base color and even lighter hash markings on the edges, and then bring it all down with a sepia tone wash. I used it on a Bones cloud giant which has thick leather straps, with excellent results.