Personally, all I can say is that

You will earn merit on the most unexpected circumstances.

I am just replying earnestly to the posts of other people and lo and behold, I get my very first merit.
All I remember that time is I am just being sincere in giving a helpful reply and not minding if I will earn a merit or not.  I am just really want to help the OP of that post that time and never expected to gain a merit.

Hence, I just want to advise you just continue pursuing your growth in knowledge by reading and helping others in return.  
I think if this will be your focus then you will gain something better than ranking up and gaining merits?