[jimsloth]

The washing is the key (imho) to any and all toy painting. I use dawn dish soap, but I'm sure other dish soaps work as well. Afterward make sure it is fully dry. Use a hair dryer to speed things along if you want. (I always run into their still being water trapped in the unsplit torsos I'm painting, and it f-s me up when I randomly get a drip of water through my fresh paint)

The type of plastic/toy does influence which paint I use. I started out painting transformers, and the Model Masters enamels actually worked for me on the hardest/most brittle type of plastic they use. Not on the new Joes or anything more rubbery.

As for M.M. acryl metalic blue, if you don't mix it thoroughly you are basically only getting the clear blue part of the paint. It separates out into a silvery paint at the bottom of the jar and a clear blue above (most of the jar). If you run out of the silver part at the bottom (which I've done with the gun metal), you can either mix in more silver, or paint silver on the figure first, then go back over it with the blue. It will stick much better over a previous layer of paint than just straight on the fig.