How do I fix a squeaky or sticking door?

For squeaks, put a few drops of oil or spray lubricant on the hinges and swing the door a few times. For sticking, find the rub mark, tighten loose hinge screws first (that fixes a lot), and only plane/sand the edge if needed. Swollen doors from humidity often free up when it dries. It's a quick, satisfying handyman-level fix.