The focusing hood

Around the camera there is lots of light that makes it hard to see the image on the ground glass, even if you use fast lenses as I do. You may, as photographers of old would, put a piece of black cloth over your head and the camera to keep stray light out. But if you are in the open and there is some wind, it may be hard to keep the cloth in place.

Instead you can make a cardboard box with a little opening to look inside. Paint the inside black to minimise stray light. And while you make the box you might as well provide it with a mirror that turns the image heads up and makes it possible to look into the box from above. This is practical if you do not want to use a very high tripod.