How do I prepare for gate exam from first year itself in automobile engineering

As I always say that first year is too earlier to start GATE. You will learn GATE syllabus in 2nd and 3rd year of your engineering so the right time to study GATE is 3rd year. You can go to coaching classes or can undergo self study, coaching classes will help you to save the time that you spend in leisure purpose.
Self study is also better study but you need a great involvement and interest unless you dont have it you cannot concentrate you start boring the subjects.

Hope this helps!!!!