How are previous papers helpful?

Being from a CS background, I'll give you the following algorithm.

Step1: Collect quality GATE material if you plan not to join a coaching Institute. Made easy has good materials and you can easily find them online.

Step2: Buy ample stationary as you would need. I thick copy for each subject is what I suggest.

Step3: Lay the foundation first i.e. make your plan of action. As in what time to study. How to study. I would suggest 4hrs a day only for gate is enough.

Step4: Complete the theory part thoroughly at first one chapter at a time. Mastering concepts is a must.

Step5: Solve previous year questions of the chapter you finished.

Step6: Repeat steps 4 and 5 for each chapter.

Step7: Once done with all chapters, sign up for mock test.

Step8: Do self-evaluation after every test.

Note: Revision and consistence is a must.

Also, keep at least one month for emergency reasons.

I hope that helps.