Aside from the obvious classes in psychology itself, it's a good idea to do two things. First is to be sure to take classes not only in General Psychology, but also in various branches of psychology -- Abnormal Psychology, Developmental Psychology, Cognitive Psychology, Physiological Psychology. You'll likely be required to study the history of psychology, statistics and experimental psychology, such as the design and interpretation of focused psychological studies. The other thing you should do is take classes in the sciences including Chemistry, Physics, Geography, Mathematics, Statistics, Anthropology, Economics, Government and Politics, or Philosophy. Having a deep background in sciences will add much to your ability to understand and appreciate how the human mind works. Human beings are not just isolated entities, but rather the result of the interaction between them and the world around them. And you'll enjoy learning all about it to appreciate this.
There are two approaches to answering this question. First is the official, university answer, and the second is my answer based on my opinion. You can make your own mind up as to how valid each is. Basically, a psychologist is different from a psychiatrist in that a psychiatrist is also a medical doctor. This requires a whole different set of preparations and education. A psychologist needs to start in liberal arts and include psychology classes as far as they go. My personal opinion is that a person who is counseling others on aspects of life will benefit most from learning as much about the world as possible. This is obvious limited, since none of us has the capacity to learn all about everyone. However, learning about as much of Liberal Arts as possible is a good way to enable this. Take whatever you like, as much as you like. I was very fortunate to get a scholarship that the folks who granted it were not expecting to deal with a person who wanted to learn a whole bunch of stuff in as many areas as possible. For folks who are not as fortunate as me and have limited funds, I would recommend first looking over the basic, minimal requirements for a psychology degree. Then I would look through the liberal arts electives to meet the requirements but to cover as much latitude as possible. I really believe that this would 1) allow you to understand more of your patients and 2) make you happier. Even if you don't like a particular field of study that may overlap with the life experiences of one of your potential patients, you would have a better understanding of their point of view. And that is immeasurably valuable.
You need to take all General course, but also class that will help with your studies. All Psychology course, philosophy classes, and my be counseling course . I would say take a few education calls and course for human understanding.