I'm liking the skin colour with the shade of lipstick--dramatic. Liquids are hard. Could I suggest that you might find it helpful to just draw a single drop of water on skin or some surface so that you can study how the highlight, shadow and transparency work together to give the effect you're after? It's tough to work on a portrait as complex as this and figure out a technique like drawing liquid at the same time--recipe for frustration.

I like the painterly brushstrokes you get with your skin tones.