When you photograph anything flat such as this hand made paper from Burma, make the back of the camera as parallel as possible to the subject. That gives you the ability to have complete depth of field at any lens aperture. When shooting patterns, art work, tapestries, weavings, chipped and pealing paint, etc., it is important that every square inch is tack sharp. As soon as the camera becomes oblique to the plane of the subject, depth of field becomes an issue. Then you need to use a small lens aperture, and that in turn means a slower shutter. That forces you to use a tripod unless you raise the ISO, and obviously you want the lowest ISO possible for maximum picture quality. That's why making the camera parallel to the subject is important.