TEARS AND "WETNESS"
This is a tutorial I made because someone wanted to see how I make things like tears, slime, "wetness" and this kind of stuff. It's relatively simple, but anyway:
Here's an example of how I use to color a "tear".
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     1. Start with a white oval circle.  | 
    
     2. Use "Airbrush tool", adjust the "Pressure" to something low (for example 25%) and color the inside of the circle with the skincolor the character has, so the edges remains white and it looks a little "transparent".  | 
  
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     3. Use "Airbrush tool" again, and place a little white in the end of the "tear". Finished! ^^  | 
  
Here's an example of how I use to color "wetness"
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     1. Start with coloring the white area.  | 
    
     2. Use "Airbrush tool" and color a little around the edges to "soften" it up a bit.  | 
  
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     3. Use "Airbrush tool" again, adjust pressure to for example 25% (like in the example of the tear" and color the inside. Here you can experiment with what areas should be light and dark and so forth.  | 
  
There! I hope you found something useful in this ^^