I downloaded a trial copy of Photoshop CS5 so that I could play with some of the new painting features on my tablet. I'm still trying to find a comfortable painting technique with photoshop beyond just coloring a scanned drawing.
My biggest complaint (in any version of photoshop) is that it's a pain to adjust the color you're painting with. I want to paint a bit with, say, a red, and then make it a little darker or lighter the way I would on my paint palette by adding white, black, or a complementary color. If I could have the big square color picker you get when you click a paint chip out all the time that would be great, but that's a modal dialogue and it's inconvenient to get at. The HSB sliders help a little (RGP is worthless) but they are small and hard to adjust on the tablet.
I thought maybe I could put my color in one paint chip, black or white in the alternate, and then use the brush settings to mix the colors with pen pressure. Here's what I got:
This kind of works, but you never get the full strength of the back color. Plus you're limited to mixing two at a time.
CS5 also has a new mixing brush tool that works a bit like Corel Painter's oil brush tools, just without so many settings. I had a go at those on a reference photo and came up with this:
This worked a little better. However, you get this smeary finger painting effect that looks very "computer painted". Ick! Maybe this will work better if I find a brush I like.
Practice practice practice.