What are the tips for GATE CSE preparation?

First step towards preparing for any exam is
Go through the official syllabus
See previous year questions
This will give you an idea about subjects you have to study and what kind & level of questions are asked in exam.
Next most of you may have a doubt
Coaching or No Coaching
This depends on you. What i mean by this is that if you have your basics cleared, there is no need to join coaching. Sharpen your concepts by studying weak areas form standard text books.
What if basics aren’t cleared ?
Then you have two options. First, use either NPTEL or other top institutions free video lectures . Secondly, join a good coaching. But even if you join coaching for some subjects like computer networks, computer organizations etc you should read standard books.
Which books to follow ?
How to prepare?
If you have already studied a subject for semester exam or you have a rough idea about that subject, then look at previous year questions. Why? This will give you an idea about what is asked in GATE CS paper and you can filter out important concepts from exam point of view. After this study some topics from standard text books and then use below sites for question practice and revision
GeeksforGeeks | A computer science portal for geeks
GATE Overflow
Unacademy - India's largest learning platform
If you are unable to understand any concept you can search that topic on Youtube.
Join a test series or not?
Joining a test series is extremely important. Why?
Teaches you time management
More practice
Helps you find out weak areas
But be careful as many of the test series have errors.
Remember, two keys to succeed in GATE CS exam
Clarity of Concepts
Practice
Best of Luck
Footnotes
[1] Subham Mishra - Unacademy
[2] Recommended Books for GATE Computer Science
[3] Preparing for GATE Computer Science in 45 days