For minor messes shovel up the contaminated dirt into a 5 gal bucket and haul it out. If money is no object the marine industry has a lot of oilzorb stuff but it ain't cheap. also check with a safety supply place (sells fire ext, hard hats etc) they usually sell spill stuff. Oilzorb pads, booms work great for pulling oil from water but pulling oil from dirt is a different ball game.
For prevention fix your leaks before you go and keep your rig maintained and painted side UP.
"Don't mind me. I'm just here for the alibi"