You should score more then 180 marks in WBJEE to secure a top 50 rank.

It is very good that you have aim so high but to acheive this goal hard work is required. You should be dedicated and self motivated.

To start with your preparation you should be aware of the complete syllabus and exam pattern of the exam. You must know the imprtant topics of the exam weightage wise.

You should refer previous year papers to understand the exam pattern and level of questions asked in the exam. Sometimes, you get direct questions from previous year papers.

Managing time is one of the most important factors that would have a bearing on your score. Take as many online mock tests as possible to master the exam time. With the help of complete mock test you will also get to know your strength and weakness. So, you can work upon them. It is very important to practice as much as you can.

Give proper time to revision. It is very important that you revise daily.

WBJEE includes negative marking. So, it is recommended that you avoid making guess in the exam.

All the best for your preparation nad the exam!!