I made several rules how to write posts to get merits:
1) Write posts on a topic that you know a lot, do not write posts on topics unfamiliar to you.
2) Your post should be useful to people who read it.
3) Posts should be interesting and not long.
I think if you follow these rules then you will get a lot of merit.
Sorry for my bad English!
Well, in theory yes, you have to write some quality posts to get a merit.
but in reality, giving merit is like giving trust to someone. this is because merit is available limited.
you can only send 50% of your received merit from others.