Hi @sripo ,
I would like to take a minute to answer it .
At first be thorough with the syllabus , depth and breadth both matter very much. Then start solving PYQ's , by solving it doesn't only mean to get the correct answer , but to know exactly how you'd have approached the problem in real time(One thing which I didn't do much) . The concept behind the problem should be clear , and you must dive deep into the very minute details about the problem .
Once you've a habit of it , and have solved PYQ's thoroughly , you can then start giving test series , the best I know with minimum errors and non-mind-boggling problems(here I am referring to non-legit ones) is gatebook test series , the questions are very good .