if youre undergrad in america, youll likely have to take a standard set of courses in the beginning, like psych 101, intro; statistics, experimental psych, developmental psych (maybe 2 semesters).. the some electives in things like addiction or abnormal psych or cultural psych. if you have a univ or college near you, see if they have a course catalogue online or in print (if they have one in print you should get that instead). you might even be able to make an appointment with a counsellor or department advisor to give you some help or even get in on some projects before other students at your grade level get to. good luck. if you have several colleges or univ to choose from, i think the first thing to do would be to check out the psych dept websites, and see if the instructors are doing any interesting research, or specialize in areas you like. then, order some course catalogues with descriptions. the course catalogues will likely have a description of required and elective classes for that school, for different majors or subspecialties. then if you like, you can call an advisor or whatever phone number is listed with the psych dept, also likely to be in that same course catalogue. or you can just find a number on the website and make some calls. people are often more than happy to help someone interested in persuing higher education.

If you're in the UK the first thing you'd be advised to do is an A'level in Psychology. Not a necessity but should help you decide if its what you really want. You should be able to get on a Psychology BSc at university with BCC grades in 3 A'levels, although this is a just about minimum. After you've gotton your Psychology degree you'll need to get practical experience working as an Assistant Psychologist for about 3yrs, you will need some NHS experience. After this you should be able to get onto the Psychology Doctorate. Once you pass this you can work as a Clinical psychologist. There are a few other routes if you want to specialise in other areas such as Forensic but this is the most straight-forward.