From around the age of 9 to around 16 I regularly washed the neighbours cars (around 5 people each week) for a few quid. Made me a nice £60 or so a month which I'd blow on video games or clothes. On top of that from the age of 12-15 I had two paper rounds which paid awfully but I did appreciate the money.
After leaving school I started a part time job at a Garden Centre on the tills and as a trolley boy. It initially started as a Saturday job but I did one or two Saturdays and wanted full time work, so I asked if I could work 5 days in the week instead and they said yes. Result I thought! I was allowed to work as many hours as I wanted and if I wanted to, work the weekends as well. I did some long shifts there, but actually loved it most of the time.
I sidestepped the supermarket and fast food scene as an unskilled worker, I don't think I could have coped with either of them.