Hi sravanskarri, are you writing this Nov 7th ?
Ideally all that you need to be confident of "The Symbolic Meaning associated with every variable in a Mathematical Equation"
Since Strategy is not acquired in a short period of time and without sufficient practise, its not an easy task.
When your technique of using formulae is good, try to focus on the Symbolic Meanings, that would help you apply equations swiftly. Any conceptual understanding like general ideas about things can also help you.
Hope this helps you...