Okay. I've never seen or heard of a shock manufacturer sending anything other then .010" compression stacks out the door unless the user specifically requested something else.  So just start there and spend and extra $40 and get a couple of extra shim stacks so you can play around with stuff.

Compression:
Valve stacks are very much like leaf springs. The longer ones flex easier than the short ones and of course the thicker they are the stiffer. But the similarity doesn't end there. On leaf springs the top leaves are typically used during normal drive or street conditions where the bumps are small and the heavy leaves are there for when you load up the vehicle. The same is true for valving. Top shims for little bumps, lower portion of the stack is there for big bumps. If the little bumps are nice and soft but the big ones are blowing through the shocks, then you need thicker shims at the bottom of the stack.