Dear aspirant,

It's great that you made a decision to start preparing for gate in third year. You can join any coaching institute or can take pdf courses and then you can take test series of various coaching. Other than this foucs on semester subjects as they are in the course.

GOOD LUCK. 

• Know syllabus completely
• According to weightage mark topics and do well prepare them 
• Revise previous years question papers may there is a chance of getting similar questions 
• Note important formulas and points and revise them throughtly 
• And prepare timetable and follow it 
• Be focus on what your studying 
• Know exam pattern perfectly