First, You don't have to get scared. 

It is very important to be self motivated and dedicated. Don't loose hope.

In last month you should focus on the topics which carries more weightage in the exam. You can make your important notes which will help you at the time of revision. You can also solve as many as MCQs for your practice.

 You should have your basics strong. Take NCERT help to work on your concepts. It is very important to solve all the exercise given in NCERT book. 

Solving complete mock test series is very important make sure you do proper analysis. So, that you can improve your performance. It will help you to know where you stand among other competitors. Try to increase your speed as well.

You should try to score more then 230 marks in JEE Main to get top branches in top NITs. 

All the Best for your preparation and exam!!