So, you have no idea how to pick a career for your future. This is a place where at least 80% of people will be at at some point, as asking 17 and 18 year olds to pick a career that will define them for the next 40 years is, well, a really bad idea. How many 18 year olds have any real clue what they're gonna do for the next 4 years, let alone 40? That's why we're here to help you make a semi-informed choice.
First, lets get one big concern of many out the way: You are not locked into a career you pick early in life. The best thing to do here is to develop skills or get a major in something thatis dynamic and has a wide reach of career options. Typically this means majors such as engineering, tech, or business, as these degrees tend to pay a lot even if you don't end up as an engineer.
With that out of the way, the best way to actually pick a career is to see if it fits into 4 criteria: It's something you enjoy/are passionate about; it's something that pays; it's something that is valued in the world/makes an impact; it's something with a large job demand. Now, obviously you can prioritize one over the other. Having a career you love might be way more important than money.
So, how do you find a career like this? Well, first we have plenty of roadmaps and coming articles detailing majors and careers and how some are better than others, but for independent research you first want to start with the numbers. The BLS has great data that will always provide a starting point. Next, you want to find something you enjoy. This is probably the hardest part, as most teenagers don't have much of a passion for things like mathematics or financial analysis. My best advice is to take at least 30 minutes a day to just try something new in a field that has some potential. Try doing some coding or independent math studies. You can find a passion for almost anything with time. Next is whether the thing you're doing makes an impact. Many people don't really care if their career has a major impact on the world, which is fine. Not everyone has change the world. But, for those of you that do, the best way to go about this is to look at what you can accomplish in your respective field. In pretty much every field there will be jobs that have a major positive effect on people, even in careers that have historically been known for their "self supportive" nature(finance anyone?). But, there is always a tradeoff. Afterall, you could go to that small firm that specializes in helping those without financial knowledge with things such as investments and taxes, or you could make 4x as much at Goldman Sachs. There is a tradeoff in everything. As for demand, you can simply look at labor stats or go on LinkedIn to see the number of job postings, but this shouldn't be needed, as unless you're going into a niece field the salary usually aligns pretty well with the demand(higher salary = more demand).