I'm working to get the knack of what works for me. The thing I like best for spreading the paint is an old credit card. The small spot effect is made by spritzing water on a second wet layer of paint, waiting for about 15 seconds and then blotting off the top layer where the water is.
For paint, I prefer "real" acrylic paints over "craft" acrylic paints, although I did buy a few bottles of the cheap stuff recently to Gelli print with. It's true what they say, all those folks who write about the use of paint in their work ~ the cheap stuff has a really low pigment load, meaning it's mostly binder and doesn't have much coverage. The binder is also weak and the colors can't be mixed successfully because they're already so highly mixed to begin with. Of course you can paint over dry layers of the same stuff, but they just don't work like real acrylic paint.