How do i get good marks in engineering like I used to get in classes 11 and 12?

Update: i used to get 85% while I used to study in class 11 and 12.
I am expecting similar or at least 80% in engineering.
But, at my best, I got 76%.
which many average students of 11 and 12 had got.
What areas should I focus,what should I do to get good grades?
Update 2: studying computer engineering
subjects
-electronics subjects like digital logic,electronic devices and circuits.
-electrical subs like circuit theory..
mathematics
electromagnetics
programming in c++
IN Class 11 n 12, only physics chemistry and mathematics
12 answers 12