Do any of you have a side-hustle?

I’m about to start being a classroom teacher, so I doubt I’ll have the time. But I’m playing with the idea of trying to do something on the side to make money. I just have no idea what’s feasible.

I just want to pay off my HECS and save up ASAP.

Edit: Thank you all for the huge variety of answers, I’ll keep your suggestions in mind if I have the time, or maybe in the holidays.