The official website of NEST informs us that questions asked will be based mainly on NCERT/ CBSE science syllabus of class XI and XII.

As regards to the general section of the exam, there is no hard and fast syllabus. The official website informs, "This section tests candidate's familiarity with, but not detailed understanding of, major historical milestones in subjects like Astronomy, Biology, Chemistry, Mathematics, Physics, Computer Science and Environmental Science."

In accordance with this, the JEE Mains syllabus is more or less similar to that of NEST other than the general section. I would advice you to thoroughly solve past papers of both NEST and JEE Mains. Identify what topics are given most weightage and concentrate on those topics more.

For example, the last chapters in Physics, Chemistry and Maths can be covered easily in one day. And note that most of the times, one to two questions come from these topics. All the best for your preparation! 

Dear Rameshwar,

Both the JEE Main and NEST exam is conceptual based. 

In order to prepare for your exam it is very important that you complete your NCERT books. 

To crack both the exams you need to do lot of practice. You can focus on the topics which carries more weightage in the exam. Solve MCQs for your practice. 

You can also solve as many as mock test series to analyze your preparation level at regular interval of time. 

All the Best!!