Even you make good posts and help newbies in here you won't get merit points from them as they don't have, so is up to higher ranks to notice your posts like project owners or some team members of that particular project and and give you some merit.
Helping members and then expecting merits in return is not right in my opinion However, you still get rewarded for this. Suppose a new member asks a query here and you provide a good reply to his query asked. Whenever a senior member of merit source will notice this, you will get rewarded. I think once you get to the member rank, you already become aware of the sections and posts that have higher chances of getting merits.