I would suggest you to devote maximum time of yours in previous years and sample papers as this would be the best source to know all the important questions and once you are done with these it is advisable to start doing online mocks as these would be teaching you the time management skills during the exam and along with this, when you go through the test analysis report properly then it would be showing where all you are still lacking and accordingly you can revise the same. Also, if you talk about Barron psychology 7th edition then yes, it would be helping you in a right direction you can consider it.

Hope this helps!!!