Hi, you can start by practicing previous years papers that you'll find online easily. You don't have to prepare anything extra other than what you have studied in your graduation. Just revise all the content you've learned in 3 years if you had ba or bsc in psychology.

Generally the exam syllabus and pattern differs from college to college, so you can check the University website you wish to take admission in and check the syllabus or the exam pattern of that particular.

Good luck