Over on the 3A forums they've started a thread on painting and customizing DIY Vinyl figures since they have several on their way to us fans (all of which will end up in here as soon as I receive and paint mine). Many of the members are new to customizing and were requesting info from the more experienced modelers on the board (and there are some AMAZING customizers on there). I don't do as much chop stuff on my work, but I've done more than my share of painting miniatures and action figures. I posted a Dunny I did (whose original paint job annoyed me to no end... the only blind box from that wave I did not want, of course) as an example of wet blending.
Wet blending is a technique I've known about since my days at "The Shop" but never attempted until a freak accident last summer proved it wasn't as hard as it sounded. Wet blending is exactly what it sounds like, you're mixing your colors right on your figure/miniature/etc. It creates far more subtle tonal shifts. Last summer, while completing Tess' custom Gaz, I rushed the background and ended up painting a new layer before the previous layer had dried. What resulted was a smoother transition of color (I was working on creating a lighting effect) than I ever would have achieved through traditional tonal layering.
I attempted the effect a few more times since then, my most recent, and favorite, was the aforementioned Dunny. I recreated the Dunny as a zombie (a stretch for me, I know). I mixed a few tones of a very rotten green and as it was drying, added in patches of yellow to create the sort of horrible discoloration you get as skin rots, thins and separates. After that dried completely, I added a bit of dry brushing for some thin, semi translucent white patches. After that dried I went in with the original dark green color and painted in small holes in the skin, creating the appearance of exposed regions beneath the surface. I was very happy with the results as it gives a very organic look while still being a bit more artsy than one would achieve when shooting for full on realism. Its useful on anything from simulating distressed, rusty metal to rotting flesh (obviously) or simply to make something more interesting than flat colors permit.
Its much easier to see on the back.