Hello friends,
I've been asked this too many times by many users on the forum that what do they need to do and what they shouldn't in order to make some meritorious posts and grab the opportunity instead of ruining it for themselves.

Let's start:

Do's -

• Always discuss on topics you are familiar about, never post guesses as that won't get you any merits (take it as salary for example, do you ever get paid for your guesses? No, right? You need to work for it).
• There are many interesting topics to know about, and so there are different boards as well, to make you learn more about these interesting things related to Bitcoins and its technology, the blockchain and the trades that happen anonymously over the network.
• Try to make your posts understandable with better quality English as even if it's not your first language, you should be able to make the end-user understand what you are trying to convey in your message. There are many online dictionaries that you can prefer to learn more about the words you post, never go all in on Google Translate because it breaks the words too much and won't always give you accurate translation (you might get better accuracy sometimes, though. But it all depends upon the length and meaning of the sentence that you want to make people know about).
• Try to watch out posts in Meta section of the forum as it is the best place to learn more about, and even get merits on your posts as I have seen many users saying this, and it's a fact that Meta is by far one of the most disciplinary and knowledgeable sections of the forum.

Don'ts -

• Never ask for a merit (unless you are given the vantage to do so - saying this based on the number of threads that allow you to try your luck and get some merits if they feel that your posts are meritorious). Don't ever dare to PM anybody for a merit as it might get you into trouble - especially a negative trust. Users are needed to earn it by showing that they are actually working on it, so try not to spam and make meaningful posts.
• Never ask questions that have been asked a 100 times already. It's like - you are new to the forum and you don't know what is Bitcoin and what is blockchain and how it all works. That's such a basic question which comes to a newbie's mind and hey, you feel like you should post it and ask it better to the community, right? Wrong. Try to use your fingers a bit before posting that same question again and again, GOOGLE it and check if there's already a thread which has been answered with like 1000s of replies. Yes, I mean it. There are a lot of threads with the same question and that's what we call as SPAM. You have the right to ask, that's not an issue. But, be smarter and try to get your queries resolved by trying Google.
  And if you'll ask (which may never be the case in such situations) - But hey, I don't get a satisfying answer in any of those threads, what should I do now?
  Come here and ask us, we will definitely entertain you and try to satisfy your eagerness to know more about the crypto world.
• It's something that's purely based on luck (like many posts are yet to be merited but aren't done so due to being unseen in the eyes of those who understand the value of such posts. Don't feel bad if you know that your posts are meritorious and haven't been merited yet, I will be updating this thread with a list of many threads where you can try your luck and if your posts deserve a merit, they will absolutely be rewarded (if they are really something that contributed to the forum members in a much better way).

So, why do I need merits?
I already told about this before, telling this here once again that merits are needed to gain higher ranks.
If you are here to contribute to the forum by heart (in a selfless way), you don't really need merits because even with lower ranks, you can do your work and eventually you will be rewarded by all the high-end users here. But, if you want to join a signature campaign and gain some more for your limited posts (which may be contributional or may be spam) through higher ranks, you need merits. By saying that, I never meant that you need to remain high-quality till you reach your desired ranks and then tank your quality under water once you become n member and join a signature campaign. You will still need to remain focused on how to keep your posts always at high-quality.

I hope this satisfies your desires to know what you need in order to get merits - BE MERITORIOUS AND GIVE US A CHANCE TO GIVE YOU MERITS.

P.S.: I've found one more thread that was made way before me with a guide to get merits, however I am not deleting mine as I believe that there are a few more points discussed here. You can find the thread here - TMAN'S guide to getting merit.