I'm a little confused. I've always been told some light, natural hand gestures are good in a monologue. However, I've been told in auditions to start over WITHOUT the hand motions. If they don't want you to use any hand gestures, how do you make your stance look more natural?

This is a classic acting problem with a classic acting answer: objective.

The answer is, you don't think about your hands. You think about what you're trying to get from the other person (the person you're addressing the objective to). Everything else grows out of that.

If you're thinking about what your hands are doing - or not - you're not thinking about your objective. And whether you use no gestures, selective gestures or many gestures, it will always be wrong - so long as it doesn't come from your desire to achieve a result from someone else.