No one has mentioned the attributes box. When I am playing in Bryce, I seem to spend most of my time working the numbers in the attributes box. Everything by the numbers! Keeps your objects where you want them. ALSO, very important: when slecting an object, always use the Ctrl key and select from the list, even if there is no more than one object under the mouse. This prevents you from moving the objects just by selecting them. I have made this a habit and now I never select objects with a single mouse click.