We cannot say it is the toughest, but it is the trickiest one. This is because it has only 65 questions with 100 as maximum marks that decides your fate. Add to that the vast syllabus, unpredictability of questions and difference of toughness of questions in different sets. These all leads to a very unpredictable type of exam. 

Here is what you have to do to make this exam easier:

1. Complete the whole syllabus with proper short notes for revision till the month of november or atmax december.
2. If you are joining coaching, then well and good as you will make handwritten notes parallely with subjects. If you are not joining coaching then purchase handwritten notes of toppers preferably from made easy or ace and read them seriously 2–3 times atleast while making short notes parallely.
3. Invest your money in buying previous year question paper set with solutions not only from your branch but also from other relevant branches. Eg. If you are from EC stream then also purchase from EE and IN if possible. Solve previous questions till you get comfortable with them.
4. Remember, revision is the key. If you dont revise then there is no point in solving ‘n’ number of questions or joining plenty of mocks. So revise till you get comfortable with particular subject.
5. Join a test series from two different institutes and solve each test like its your final exam. Made easy test series is a must as there are lot of students who enroll to made easy test series. So you will know fairly where you stand in between the competition. My other suggestion would be ACE as their questions are much more relevant to actual GATE exam. But other institutes are also good.
6. Refer standard textbooks only for difficult topics or the topics which you are not able to understand properly. Do not refer everything from textbook. Its a clear waste of time.
7. Join a Telegram or facebook or whats app groups for some quality questions (this is optional though)
8. Finally, it doesnt matter how much hard you follow above points if your performance in the actual exam sucks. So make sure that your final performance is good. Give full length tests very seriously to make yourself comfortable to sit for 3 continuous hours.