Which topics I choose for getting 300 marks just I want bams seat

BAMS admission is through NEET Entrance Exam. To score a seat in Government colleges you need to devote your time for study with hard work.

I would suggest you to go through well with NCERT books properly because it will help you to build your concept. Here are some important tips you can follow for the preparation of NEET.

Know about the exam very well. Like the eligibility, syllabus etc. This will help you get an idea of the important concepts so you can aim your preparation for NEET accordingly.
Very important to do is- Create a study table and make it in slots with a short break in between
Set your routine in a way that you target the difficult ones first and then go to the ones you can handle well.
Prepare well, master with basics, keep revising. Make notes of important formulae and equations while studying. Once through with a chapter or concept, attempt the sample questions based on it.
Since the exam will be devoid of any direct questions, it is important to give an honest attempt to learning and understanding the content.
Keep giving online/offline mocks. Work on your strengths and weaknesses. Analyse your performances. Give enough time to weak areas and master them.

Good Luck!