There is no such thing as fastest way to earn merit. it really depends on you and your knowledge that you have. It depends on the post that you post. Post that must be informative to others. Other who really finds your posts helpful and informative will give you merits. There is No merit for low quality posts that some people make in this forum. their account doesn't really rank up. Always try to make good posts. and try to be helpful in your writes up. The merit will come when it has to come and where from it has to come. Just keep up the hard work and it will pay you someday.