My wife wanted me to hang some fun signs on two doors in our lower level. The problem was that the doors are hollow-core and are only 5/16th of an inch thick. You can’t screw something into them and expect that solution to work. Here are some easy tips to get a professional result. See photos below.

I used a scrap piece of wood, a few shims, and a level to act as a support surface.
Here, my son is helping hold up the sign so I can eyeball it to make sure that it is at the right level.
This sign had two holes for screws.
I used a grinder and vice grips to cut down the screws to their heads. They would be used only for aesthetic reasons.
I glued the signs, and in this case I also glued in the screw heads.
Job done. Fun signage complete!