Wipe all excess water, mud, and sand from the upper tubes, lower tubes, and crown area with a clean rag or bristle brush (Park makes a great one!).
Wet a rag, or spray your fork with a light coating of solvent or degreaser, and wipe the crown, top caps, upper tubes, dust seals, and lower legs clean.
Apply a small amount of fork oil, RedRum, or Teflon-based lubrication to the upper tube area nearest to the dust seals. Cycle the fork a few times to circulate the lubricant. You can even gently pinch the dust seal, nearest to the upper tube, and add some lubrication (mentioned above) to the inside of the dust seal. This will lubricate the foam ring.