I had two jobs in high school and learned a lot from them.
In the first, I was a temp worker for a P&G re-packaging facility. This means some temp agency was paid $12/hour and they passed on $9/hour to me. The job was backbreaking, in intense heat, and with very strict management rules (e.g. no lunch break, sitting down for even a moment was grounds for being fired).
In the second, I did lawn mowing for individual families for $20/hour. I found them by referrals and networking, and could control my schedule for when I went to do jobs.
This taught me that being creative to find good jobs was super important.
In college, I found a series of high-pay, flexible or comfortable jobs. A few examples:
$1000 for one week's work to hand out 2 pallets worth of coke zero to college students. I was allowed to keep the extras and ended up with a 1 year supply of coke zero for myself and all my friends. Oh, they also gave me coupon for 1,000 free burritos and despite a very diligent effort to hand out as many as humanly possible was left with ~300 burritos and told to just keep them. Qdoba was my primary diet for quite some time.
A job selling cameras on eBay for a camera shot that went out of business. They paid me a 25% commission and had one of the largest private collections of highly collectable cameras (I sold one for $8,000). I only did it for a summer, and probably should have taken a semester off college to just do this full time and could have made enough money to significantly reduce my college loans.
A freelance role, for a German re-insurance company to write white papers for $50/hour and could create my own agenda for what I needed to write, and work whenever I wanted.