Also, go through the previous years sample papers provided by careers 360. It will help you for preparing for the exam. Click on the link below for sample papers -  https://engineering.careers360.com/articles/gate-question-papers. Hope it helps you.

GATE 2019 will be conducted by IIT Madras and based on previous years question papers, it can be said that IIT Madras mainly ask questions based on basics and try to extract in-depth knowledge from the students. So, the difficulty level can be minimized if you work hard and make proper study timetable and give time for revision.For more details click on the link below - https://engineering.careers360.com/articles/gate