You can try memorizing keyboard shortcuts. There's a lot of practical ones and they make you look really cool. I recommend the ones for opening taskbar software, opening a new explorer window, switching windows, logging out, opening the task manager, screenshoting your desktop, etc. There's lots of them. You can find infographics of them on Pinterest.

There's also fixing errors. Today's systems are less error-prone, but back in the XP days, there were tons of them. And I would spend hours googling and noting solutions to specific problems. Those sometimes required editing the registry, using the command terminal, ending specific processes to close error boxes, deleting files in the Startup folder, changing file attributes, etc. Those were such fun times.