Hello 

You need to mention your field i.e science/commerce/arts, on the basis of which it'll be easy for me to tell you the relating requirements for the exams.. Score.. stuff.

Well generally, the results of both class 10 and 12th matter the most, which you must be knowing. Class 11th is base forming for class 12. As to get admission anywhere after 12th there are entrance exams which are to be given and qualify in them too. So it mainly depends on both of your 11-12th class studies+ efforts to crack the future entrances. And thus it is very important to focus on your 12th and score at least 80-85+% result. So prepare well and study smart. Keep focusing n achieving your targets.

Hope this helps.!

All the Best !