As promised, here is the technique to draw the tongue.
This is just the example. If I want to paint (draw)
this

with this referent

which has the similar angle and size.
First, I complete the mouth shape, and draw the dark area like this

(normally, dark area is the darkest red)
Then, I use the paint bucket for the large area by using the color which is behind (dark red from ref)

After that, I draw the lighter part (light red from ref) by using the brush with appropriate size

Finally, I use the blur tool to combine the dark and the light together. Now it's complete!

I can also use the same way for other images,
such as this

from this referent

Well this is just my way. If you have any other nice techniques on painting, please feel free to share them. :)
19-Feb-2008
19-Feb-2008