To approach a question either write the formula of desired quantity and then put the values directly or indirectly from given values in question

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 write the main equation of that *topic* so that you can know which quantities can be deduced from the *given* values and *main equation* 

For example in questions of photo electric effect you can always *start* the question by writing *main equation* and then putting given values and checking what you can find by putting those values.   K.E  = E - W ;

energy, E can be replaced by expression in terms of freuency / wavelength

work function, W can be replaced by expression in terms of threshould frequency /  threshould wavelength

Maximum kinetic energy K.E. can be replaced by expression in terms of velocity or stopping potential.

Basic understanding like -

to cross a pole, a train need to travel a distance equal to it's length... Because pole is said to be crossed only when the guard's wagon(last wagon) crosses the pole.

I don't fear the man who practiced 1000 punch. 

I fear the man who practice one punch 1000 *times* - Bruce Lee

Practice each questions 2-3 times until you become used to or comfortable with the analytical process involved in it.

Best Wishes