Yes pastels is the way to go. Dont forget misted here and their with some black and red. .Take a good look at the boots in the REF CD you'll know where the misting and weathering goes. That is the way I did mines.
I walked with my MC's through a mixture of dirt, water and motor oil. It weathered up the soles perfectly.
For the fabric parts, I used pastels. Black, dark grey and rust brown in some areas to simulate blood spatters. I put most of the dried blood around the edges of where the toe spike meets the boot. I mean hey, what did you think Boba uses those toe spikes for anyways? Hehe.