To clear UPSC exams, you cannot afford to ignore any area. The Prelims exam is divided in two parts: General Knowledge and Aptitude.
Both the parts are of 200 marks, but aptitude is of less importance. It is just a qualifying exam, but still doesn’t mean that you ignore it or give it less time. Every subject has equal importance and needs same dedication to perform well in the exam.
But before anything else, you need to understand the exam pattern, importance of each subject and strategies to prepare well for them.
You can read the blog to know everything about UPSC exam preparation: 6 Important Things To Know Before Initiating UPSC Exam Preparation
Hope the blog helps you give your exam preparation a right direction for maximum learning. I would suggest that you should not just limit your preparation to the Prelim exams as many subjects and topics covered during Prelims are also helpful in Mains exam. So prepare for both the levels simultaneously.