There are several approaches to this.  Probably the simplest way is to play around with the specularity (Highlight) settings, which will at least give the skin a glossy sheen.  Adjusting the values can give you varying effects.

You can also buy textures with a wet look already added to the skin, which uses the above method,combined with painted or photographic details to give the appearance of water droplets.

I believe there are some shaders included with Poser 5 (may also be in 6 up) for the default people, which also give some kind of water droplet effects for the default people.  If you're using another figure, these can be adapted manually.

You can also try using the figure with a body suit.  Set the skin to some kind of shiny wetness and use the body suit to place water drops and runs here and there, using a water shader with a bump map to raise them up.  Obviously, you'll have to make a transmap to mask out the parts you don't want to be visible.  I have to confess I've never actually tried this particular method (yet) but the theory seems about right.

Coppula eam se non posit acceptera jocularum.

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