I use this App called Tayasui Sketches.

Draw Something 2 the full version with a pen or stylus.
Unfortunately, Draw Something 2 has bugs so I deleted it (DS2 Free)

I use desktop and tablet. I use scribmaster app when I'm on my tablet. It gives you all different types of shades for each color like dark reds,reglae neon reds, pink/red ect.

On my desktop I use MS paint. I always use the line tool because it is hard for me to draw with the regular pencil tools. When you use MS paint prepare to make your picture with alot of pixels.