One way to fix a loose screw in wood is to remove it and then insert toothpicks or burned wooden matches with a coating of wood glue into the hole. Allow the glue to cure, then cut flush and re-drive the screw. You can also insert a plastic wall anchor into the screw hole. When you put the screw back in, it will expand the anchor and will hold solidly.
When you process wood in your shop, it is helpful to make notations on boards so you remember which have been cut to length or run through equipment like planers or jointers. Instead of using pencils for the notes, use chalk. Chalk lets you mark the wood without marring it so you can be more liberal with your notations. An inexpensive children’s sidewalk chalk set will provide several colors so that you can color-code your marking system.