almost everyone go through this when they were/are at your position. nothing new/ nothing to worry about.
GATE does check only fundamentals of your engineering specialization.
people find it difficult coz they may not be sound at it.
Well only way getting around this GATE exam is to have your basics crystal clear.
have you every had a close look at the questions of GATE paper? if you did, you might have probably noticed that they ask fundamental questions but the thing that bothers everyone is that they are TRICKY. thats it. all they need/expect from you is to have that ability to solve the problem using the appropriate fundamentals of engineering subjects + math.
my suggestion for exams like GATE would be to start off with mathematics.
have a complete grip over it and then go to subjects of your specialization.
math i didnt mean just to practice it rather try to feel it.
okay, sounds crazy but try to understand what i mean.
suppose you are given a function, dont just try to know how to differentiate or integrate it rather try to have a insight of why are we doing it, whats the use of doing these process, what this process could physically mean.
try to always have a graphical/geometric interpretations of functions when you are trying to differentiate/integrate or trying to find maxima minima etc.
every small thing you should be knowing. for example you should also be knowing what is the difference between line integral and single integral or double integral and surface integral & even triple vs volume.
be very thorough with all these three calculus: differential, integral & vector.
similarly have a complete thorough knowledge of other topics of math. complete detail study of BASICS.
then you go to your engineering subjects, definitely first maths gonna make your life quite easy. you will realize it.
well i know things could look very scary at this point, but there is no let go if you wanna end up yourself into one of the fine schools. so you have to work hard. hard work + talent -----> success.
be very systematic. be consistent. commitment is very necessary and having a passion is must.
things are always gonna stand in your way, never gonna let you wade through easily. so, only way to succeed is "never ever give up" & have patience as much as you can. just fight it out, sure one day you gonna make it.