Hi! That is awesome that you're thinking about investing in Real Estate in your teens. My advice would be to start low in terms of how much money you're going to invest with and learn through that experience with not much risk behind it. If you have the money for a multi-family property, it will give you a lot more upside, but it can also become a little complicated to manage your first try. If you start simple with single-family homes, not too pricey, going through the process of actually buying the property, going through escrow, the inspection, appraisal, finding good quality tenants, etc., it can be very rewarding in terms of obtaining all that knowledge and less risk financially. Once you built your confidence, then you can start looking for bigger projects. Hopefully this helps answer your question :)
