I know Major G will come along and provide us with the right answers in a short while. Anyway I have completed 2 M1 kits in desert camo so far and what I did to the tracks was:
1.) Paint the metal portions with gun metal.
2.) Paint the rubber blocks with flat black.
3.) Apply a thin black wash for the metal portions first.
3.) Drybrush the metal portions with metallic grey.
4.) Apply a thin wash of flat earth mixed with buff.
5.) Drybrush the rubber blocks with flat black.
6.) Drybrush (a little bit) the metal portions with metallic grey.
7.) Light spray with flat earth mixed with buff.
Look ok to me but I am not sure if would be good to you, too.