what classes

talk to your guidance counselor, cause my school I know has a psychology class, and just recently added a class for kids who want to become teachers. It depends on what classes your school offers

A little bit of biology will be good for understanding the mind, if you are choosing to go for strudent counselling. Also the best thing that you can do is to observe your friends and more than that, your juniors because once you get graduated as a students counsellor, those who were your juniors or a little younger than them will be the one who will be comming to you.Try to observe their behavioural patterns and problems. If you are going to be a teacher, the basic science subjects will be good. If you like to teach social science subjects, then try history,geography etc. If you are going for helping the kids with special needs you have to cultivate patience and love for these children now itself. In our country only the nuns primarily go for such things since all others doesn't want to get involved in such a sacrifice demanding job. If you are the person who is willing to spend some extra hours for these kids out of love for them,then you can go for it. Some biology will be good here too. Anyway, best of luck for your future.