Hi Venemous and Unreal Pie,
Thanx for these comments about the tools. I do use a digital pen and tablet which makes my painting easier.
You're right - it does take a little practice to use this particular paint bucket tool but once you get the hang of it its simple. I use transparent color in layers usually.
If you prefer to paint the background first in a solid color, use either the fill bucket or the airbrush.
then use a transparent grey or white pencil to put in guidelines. Once you have fleshed in the real outline in an oopaque black, you can erase guidelines using the exact same background color pencil.