Go through some online courses in data science to brush up your topics. you can go for the georgia tech cerification in data science as well.

popular sites - coursera, udacity, edx etc.

Hi, If you're sure about being a data scientist, here are some options for you after 12th class:

• Bachelors in mathematics and statistics
• Bachelors in Computer Science
• Business Intelligence if you just want to go straight into business analytics.
• If you have specific domain in mind(genetics, economics, astronomy), go for the specialization in that domain and learn data science through online courses.
• Also learn about stats and computing to pursue data analytics.

All the best!