First of all, set up a study area that you use only for studying. Preferably, it should be on a table or desk- not on the couch or in bed. Before sitting down to study, make sure you have everything you need so that you don't have to get up in the middle of your work.
Keep a dayplanner. Write down the due date of every assignment as you receive it and the date of every psychology exam. Within a week of receiving long-term assignment (less for shorter assignments), create a rough schedule of when you will complete key tasks for the assignment. For instance, if you have to write a paper about reading materials you've been assigned, set a target date for having the item read, another target date for finishing any research on it, and another date for having a rough draft drawn up.
Take good notes in class. Make sure you write down the key terms and the most important points. (See tips for taking notes at the link below)
Psychology is the study of why people do the things they do. Think about the ways in which psychology relates to your life: yourself, your relationships, and the people you know. As a psychology major, this tip has really helped me understand the things I've been taught.
Come to a greater understanding of psychology by reading related materials, especially psychology journals and articles. Many articles you can find don't take long to read, and you'll come to know psychology much more intimately.