I personally wrote a lot of posts(like 200) before I started thinking about gaining merit in order to gain more from bounties.
I was mostly posting for bounty campaigns and because of interest in various topics, and didn't really think I'd ever get merit.
I thought I might as well try do something useful, since I enjoy the crypto-discussions anyway, so I wrote some guides and gained a bit of merit, which I understand might require some english skills.
However, to my surprise, I've also received about half my merit simply from actually just discussing things!
I thought merit mostly were given to people who wrote great threads and such, since it's a bit difficult to find a single post in a long thread, but apparently that's not the case.
I don't think you really need to be an expert in english, and post long detailed threads.
Instead, just discuss in topics, and make sure you contribute in some way. There's little reason to write the same response that 10 other people already has,
or to write one sentence saying something generic. Instead, make sure you interest yourself in crypto, then hang around in Serious Discussions, Bitcoin Discussions, if you're technically savvy, check the Technical Section.
I personally enjoy reading in Political section and chatting in Bitcoin Discussion, there are really great discussions going on, not everything is the "Altcoin Discussions" 500 pages-spam.
There are many other sections(categories), find one you can contribute to, on a topic that interests you, I only gave a few examples.
But, why would someone give you merit, if you only repeat what someone else has said?
So, try to simply find an interesting topic and discuss
with people, not just "generic response", contribute with your opinion/your knowledge
(although I'm a noob and only have 8 merit, so surely someone else has some suggestions
)