Stick to a timetable; Make time for discussions and debates
Timetable: Don't rely on last-minute preparations. Analyze the syllabus well in advance, and formulate a study timetable which suits you. Above all, stick to it.
Discussions and debates: Do indulge yourself in productive, quality discussions and debates from time to time, with other aspirants and your friends. This will help you get hold of different perspectives and approach issues from various angles.
Develop professional-level writing and reading skills for IAS exam
Writing skills: The thing about the UPSC exam is that studying alone won't help- attempting the paper is equally important. Thus, it is advisable to enhance your answer writing skills before the exam day comes.
Reading: Never underestimate the importance of reading newspapers and magazines. This will give wings to your grasp over current affairs and general knowledge, and improve reading and writing.
This might not be the most common tip to help you crack the IAS exam, but you need to take care of your health. It is advisable to eat healthy, and get enough rest through the day. A healthy mind is a winner already!