In some situations the old analog methods still work best. I have tried several drawing and painting apps for the iPad, but I can draw much better with a pencil. For a work I want to look really good I make a drawing and ink it. I scan it and open it in Photoshop and clean up all the lines. Finally, I paint it in Photoshop. I had much rather paint in Photoshop than have to use real oil paints, or work in some other medium such as acrylics. I can make a Photoshop piece of art work look just like an oil painting if I want to.