Dual

Complete your class 12th so that you are completely eligible to get admission in BBA or BBM and you may choose any one from management stream and you can choose any subject for your BBA or BBM as Finance, Marketing, Business Administration but you should choose according to your own choice means whatever you like in your life.
If you complete your BBA as a Bachelor's degree then you need to prepare for any entrance test so that you could get admission in MBA in any reputed institute and you may prepare for any one of the CAT or MAT entrance test because if once you qualify any one of these tests then you may easily get admission in any highly reputed institute and that is why you need to prepare well and hardly for this exam.
You should join any good coaching institute to prepare for your entrance test and give more than 10 hours everyday for study then you can score over than 90% marks in CAT or MAT.