Start by exploring! What do you like to do, what are you passionate about, what could you see yourself doing for a lifetime? If you can choose a career you love, you will be more likely to be successful. We typically put more effort into things we enjoy and are passionate about. Research what careers are available in the areas you are passionate about. Make a list of career attributes that are important to you, the find out how much time, education and opportunity exists within that career.
Once you have some ideas, one of the ways you might get some hands-on experience, is to take advantage of any career exploration programs at your school. I know this is what both of my children did and both are in a field they love, even though their experiences were totally different. One learned that what she thought she wanted to do, was definitely the right path for her, and my son was just the opposite, he didn't really have a solid plan, but found his passion through the program.
Another option is to look for volunteer opportunities that give you a variety of interactions; volunteering at a local fire station, or animal shelter, food bank, school, nursing home? All of these help you connect with people who do different jobs and you can get the chance to see if something sparks that passion in you.
I have 2 grown sons (24 & 29). When they were deciding whether they wanted to go to college or what area to go into my advice was to figure out what they like and would be happy doing first. I know that everyone wants to make a lot of money and, of course, we need money to pay for things, but when you go into a career field you may be doing that work for a very long time (I have been in the tech field for 30 years). So, you want to pick something that you will enjoy doing and will keep you wanting to get up every morning and go into work.
I would first look into what you like to do - this can be based on school classes or topics you just enjoy. From there, you can find out what careers are available that use those particular skills or cover those topics. Once you have that then you can look at each career and see what is a good balance of what you like with what you would like to make in a year.
One of my sons decided on college because his goals required a college degree. My other son decided to not go to college, but to study a particular technical area so he could work in that field. I really believe that everyone is unique, but enjoying what you do is key.