i have more then 50 posts here, but still got zero merit. I tried my best to write replies that can help other people and also me in acquiring merit but no success.
is there any strategy that can help me getting merit
Merit is awarded for posts that the meritor considers to be of high quality. As merit is somewhat scarce, especially for those of us who arent merit sources, you could even say exceptional quality. Thats why its normal for a beginner to not receive much merit. Dont worry. It would probably be good strategy to not excessively chase merit (or activity!) but to read and contribute for learning and for fun.