For preparation maintain two notes.
Making formulas book ready as early as possible is very essential. You may spend 2 days and write all the formulas first if you still don’t that book. Daily revising this book is of most importance. You will potentially lose 40 marks just because you are not thorough with the formulas. So revise it daily. By heart them. If you can’t learn them quickly read more. By hook or crook learn them.
Next coming to key points book, while revising jot down quickly some points which are essential in that chapter. Which you feel like if you remember this point, you can remember all. As you finish the subjects which you have revised try to finish this book. Also do revise this book at least once in a week.
Your formula book and key points book should comprise of:
How to prepare notes for each subject during the GATE preparations,
How to prepare notes for each subject during the GATE preparations