Tim, I believe you will find that once you start simply steering the nose of the airplane and ignoring any up/down notions, you'll find that you can fly a pattern (or other shapes). Perhaps "pushing the nose" is more apt.
And personally I believe that your arm should not be stiff with only wrist action, you should smoothly move your arm and even lead the airplane through the maneuver. It's a dance..

Typically, the flier is managing energy with his movements, smoothly trading off kinetic and potential energies. Another thing to notice is that you can extend your arm when the ship has plenty of kinetic energy (say in level flight), and pull it back smoothly to impart some energy (and improve line tension perhaps) later, when needed (say toward the apex of the flight hemisphere).
Your model will scrub off kinetic energy when you make rough, abrupt maneuvers, and this can be a serious problem, particularly with less power, wind to deal with, etc. My good friend Bill Melton would warn me, "You're dogging it!" when I wasn't flying so smoothly. The smoothness will come, and as it does, you and your model will start to synchronize, and you'll know what the ship can do and learn to trust it. Then your bottoms can be brought down to where they belong, maneuvers can be made smaller, etc - it all will come together, and that's when it really is enjoyable.
As I said, it is a dance, and you have to work out specifically just what is best for you on such maneuvers as overhead eights. Don't be stepping on your partner's toes..

Best of luck,
L.
"Complex problems have simple, easy to understand wrong answers." -Grossman's Law