First and foremost, keep in mind that studying towards your first degree takes 3-5 years. Better be well-prepared when you make your decision about what you would like to study! You should take into consideration various factors:
Answering these questions should usually narrow your choices down to a single alternative - or at least a select few of alternatives. If possible, it is always extremely advisable for you to get a part-time or summer job/internship in the field of choice. Talking to professionals also helps get you a more realistic grasp of a career in a specific area. Gathering first and/or second-hand information is the perhaps most important task for you at this point; particularly if you feel uncertain about what you want to study.
At this point it would also be a good idea to start thinking about the degree you plan to pursue. You will most probably start with a Bachelor's degree. It is not too early though, to start thinking about what will happen after your bachelor's. Do you want to continue studying and pursue a Master's degree? Would you prefer to gather some experience in the real world and continue your studies at some later point in time? Or perhaps a bachelor's degree is sufficient for your personal career goals.
Of course, you're plans are not set in stone. Over the course of the bachelor's degree you will regularly be re-evaluating your individual goals.