THE MITER BOX
When a sufficient amount of molding has been prepared, begin work around doors. Then proceed to the baseboards. The order here is important because of the angle at which these two moldings come together.
Secure molding through drywall to the wall's frame using finishing nails. Molding in corners should come together at a 45-degree angle. The wood needs to be cut precisely. A miter box can prevent the job from becoming a cobbled mess.
A miter box is not strictly a box since it only has a bottom and two sides. The sides have parallel cuts at various angles that provide a guide for hand saws. The board to be cut rests in the bottom and extends out the two unsided ends of the box.
You might want to consider a power miter saw. It is a circular saw mounted on a stand that allows the blade to pivot at a variety of angles. A power saw will considerably speed the cutting process. If you need to justify the purchase of this saw to your wife, tell her, "Not only is it good for cutting molding, it will slice and dice vegetables and most fruits." (However, I would not try this with watermelon.)