First of all know the UPSC syllabus and pattern.
Start your UPSC preparation with NCERT Books which will complete your basic
Read The Hindu newspaper daily and make notes for current affairs
Give equal time to all the subjects, pay special attention to the subject which is weak for you.
Prepare for both pre and mains exam together
Use sticky notes in your study area
Notes are very important in UPSC preparation, keep making notes along with studies.
Practice answer writing daily, it is most important
On the last day of the week, revise what you have studied throughout the week.
Keep giving mock tests from time to time, it will help you to know your weaknesses.