Keep two things in mind:
- You have to qualify GATE.
- You have to face written &/or interview after qualifying GATE.
So, your approach should be having at least basic knowledge of your subject and having deep knowledge of syllabus.
- Study according to syllabus first. Prepare short notes.
- Solve section/unit/topic tests simultaneously.
- Study weak unit/topic first, overcome your fear of those topics and questions.
- Solve previous year papers, starting from recent ones.
- Solve mock tests.
- Have at least 1–3 strong topics for interview. Prepare from beginning.
- Don’t leave a que/problem, because you can not solve it. Try it or ask it or search it. Study whole topic of that que.