Grade change around the home. Clean the gutters. Pump the water with a sump pump. Cover the earth with plastic. Close the vents if rains for more than a couple days at a time to stop external air borne humidity for entering the crawlspace. If the relative humidity excedes 60% for an an extended time, a dehumidifier also is need to stop the mold from growing. Radio shack as a neat remote humidity meter that sends a signal from the crawlspace to the living area meter displaying %RH. This makes it easy to check progress of moisture control.