Please decide a slab where everything is clarified, like users with how many merits shouldn't participate (or I believe you shouldn't allow high level members only at the first place as many of them have already earned enough merits and only those who are now down from their membership ranks should be allowed to participate.

As well, I'm now adding a few of my own threads' links here to give a few extra tips on earning merits, hope that'll help:
- Worried about Merits? I'm here to help.
- Do's and Don'ts to get merits - Read carefully!
- Interesting debate between an Avg Joe and Legend over how was life before Merits
- A query regarding Merits specifically.
- Fear about merits.

And below are the threads discussing over spam and ban to give an idea to newbies what they shouldn't do:
- What to do about spam in Forum Sections?
- Important discussion over BAN. Newbies must read.

Hope all these links will be helpful for newbies and mid-level members to learn more about what they should take care of when making posts and about earning merits.