You can crack gate either by self study or joining a coaching institute.

You can even enroll into online courses .

You should focus on practicing quantitative aptitude and mathematics questions.

Try to make short notes as the syllabus is large in nature .

The most important part is take mock tests as much as possible 

Practice previous year questions

• Practice previous year papers
• Have a perfect command on every subject given in gate syllabus
• Enroll your self to test series
• Plan your time table
• Maintain your own notes
• Never give up
• Maintain consistency while preparing.