Before my long 5 years at my current job, I did work at 2 private computer repair stores around my teen years. Customers would come in with their towers or laptops and I would give them an estimate right there. Most common problems were virus removal or back ups, with the occasional hardware replacement. It was my favorite job because I was very passionate about computers and satisfying my customers. It also where I learned most of my knowledge of computers before taking courses on Coursera.