When you are trying to put in a screw in a tricky location where you can't properly hold or support the screw, it's a lot easier if you have a magnetic screw driver with a magnetic screw since it keeps the screw connected to the screwdriver. For the cases when you want this but you don't have a magnetic screwdriver or screw, you can use beeswax instead. Put a generous amount of beeswax on the head of the screw and stick the screw driver into it. This will keep the screw and the screwdriver connected and make driving the screw easier in this case.