You may want to say in the op you only want to merit posts that are of reasonable quality, eg constructively adding to discussion or creating a thread that invokes such responses.
If you wish to do a merit giveaway, you should have your criteria which you would use to separate well meaning newbies from spammers or you can just quickly browse around the forum and find good posts to merit
Theyll likely only get cents (as a Jr member) or get banned.