Scott Christensen Recommends that you use either free flowing or more heavy bodied Acrylic Paint for your Artwork depending on your preference.
"Choose which you prefer to work with: A thicker heavy-body paint or a thinner free-flow paint. They both work well and can be mixed together with no problems. The thicker body paint needs more water and medium, but gives you a bit more control when mixing colours. I like to work with both make the choice depending on what I am about to paint."