List the fields of study that are of interest to you and come up with a list of courses you would consider studying based on these interests. Add the topics that you were most interested in during school as well as jobs that you envied others for.
The internet, newspapers, television and people around you are the best sources of information. Check online about the courses you are interested in and find out about the career prospects and the other info.
To avoid making mistakes, make sure you review the course outline of the course(s) you want to apply for. Have a look at the subjects you would like to undertake and the types of learning, assignments and examination tasks involved. This will enable you to form a rough idea of what lies ahead for you.