I remember the time before the introduction of merit when we just wrote in the forum without burdening ourselves too much with others and what others think of us.
I still post like that, and I suspect many of the other top merit earners do too. It is pretty easy to spot people who are posting in topics they have no knowledge or interest in for the sole reason of spamming their signature or phishing for merits. My biggest tip for earning merit has always been to forget merit exists and simply use the forum as it is intended - to learn, read, ask questions, and discuss.
Not many users gives merit points to newbies just because they are newbies and they know you'll make him/her Jr.Member if you'll give 1 merit.
There's actually a fair few of us (myself included) who spend time and go out of our way to track down good newbies to give merit to, which you can see from this thread:
https://bitcointalk.org/index.php?topic=5034141.msg52227889#msg52227889. I have no issues ranking up a newbie to a junior member and giving them signature privileges as long as it is clear to me that they are here primarily for the reason I outlined above - to learn and discuss - and they aren't here solely to abuse that signature. As Loyce says, utilize his thread to report any good posts you think are doing unmerited.