A lot of part-time / flexible jobs in:
- sales / retail businesses (potential discounts / perks at most clothing stores)
- restaurant businesses (server, host, barista, ice cream scooper, kitchen staff, etc.)
- grocery stores (cashier, bag boy, stocker, etc.)
- driver (uber, lyft, etc.)
- food delivery / courier
- gym (great perk of getting free membership!)
I'd say to find something you have an interest in or that could relate to your future college major (if you're going that route).
You could also volunteer or do an internship if it's a field you're interested in but that may not have any job openings. Good luck!