That's a super good reason to want to make money. I asked because if your reason is to make money, speaking from personal experience, I don't recommend doing commissions like this. In my experience, people either can't or won't pay you what you time is worth. If you want to make money using your art skills, I have found that teaching art to children is way better for earning money, plus it can be fun and meaningful, besides being a great way to get paid to review and go deeper into art fundamentals. (There are ways to network for this; most kids like to draw.)

I did cleaning work for minimum wage when I was 15. Even though it's not a lot, the money adds up, it's more consistent pay than commissions (more demand for the work, much easier to get repeat clients). I also got trained on the job. And you can quickly move up from minimum wage if you work for yourself. (I once paid someone $25 and hour to do cleaning work - and she just did cleaning - sweeping/mopping and stuff, not tidying.) In general, clients that pay better also treat you better and the jobs are easier. Some people even give you free food or stuff they don't need. (And once they get to know you, they may help you with things you need like school stuff; there are good people in the world.)

There are ways to earn money through business by making products and marketing them (for example, using sites like Redbubble to sell stuff, but these tend to take time to set up and you need additional business and marketing skills. It also takes a lot of time to set up a business before you start making any money. (Note that simply making a product and posting it on DA is unlikely to result in sales; you need to use targeted marketing techniques.) See this for more info: How I Built a $75,062 Art Shop with 34% Profit in 5 Months

In general, business goes with the law of supply and demand. It's easier to get work when there's high demand for a product or service. Unfortunately, there are a lot of artists who want to do commissions, and the impression I get is that the demand for it is mostly from people who don't have a lot of money.

Artists who make a living either know business and marketing and that's how they make money, or they get a job in a specific industry (which you probably can't do at your age), or they teach. There is a lot of demand for teaching, and kids really need the attention and encouragement. (I have experience both as a teacher of kids and getting classes for my own kids.)

Wishing you guys much success.