Just got me a testors air brush. I know thats a cheap one, but it will be fun to start with and see if I can do this. My questions: How do you get the lumps out of paint that has been sitting awhile? shaking them for hours is a pain. How do you know how much water to put in the paint to thin it? Just a few drops or ? I'm using acrylic paints. Any suggestions on getting started would be great.