There is no ideal strategy for GATE preparation. As long as you cover all the topics, any strategy should work. 

*allotted a week for each subject. This includes studying all the topics, going through standard book back questions, coaching institute material exercises etc. 

* Go through the GATE previous year questions. 

*If you are really talented and in constant touch with your subject basics, I would suggest a month preparation. If you are an above-average/average student, it is best to give 3-4 months preparation.