Looks like you're getting some decent results.
As to a recommendation, there are two things you're dealing with: subject (story & character -- what you are painting about), and the other thing is the mechanics of making it look right to your eye.
I think you're going to pick up the handling of ArtRage pretty rapidly. Play around. Everybody's got different ways to go about it.
As to the scaling, you can work large and size it down rather than up. That may work better for you. But you will find that if the continuity of the strokes change from the resize, it may not match the rest of your pic and look pasted on. So the solution is usually to do it all in context and learn the essential things about drawing and painting so you can put in those marks that describe the form you're painting -- like the head, like the boots, etc.
Doing it more and more, you'll find it comes easier. Be patient.
I can tell you are a thinking kind of fellow, so everything you do will take you forward by lots. You will learn from everything.
Have fun with it and look at how other artists have done things that you are taking on.
"Not a bit is wasted and the best is yet to come. . ." -- remembered from a dream