Be active. That's the only way to get armor points the right way. Play games, leave a constructive comment on them, post in the forums frequently. Points can't do anything for you, though, except you unlock armatars and it increases your e-peen.
Almost everyone in the leaderboard make their points by keeping a lot of friends and talking them with comments daily. But since cormyn is here that's something that could get you banned, so I'd say the best way is to use the support&suggestions forum a lot. If you lurk there and you get to be the first to answer most questions you'll get lots of points soon. Another good way is the wepr, since people there just repeat the same arguments over and over, but it can really get exhausting after a while.
Being active, rating and commenting games, talking in forums, making friends and commenting them all make AP add up pretty quickly but acmed is right, sometimes it's an addict thing.
Almost everyone in the leaderboard make their points by keeping a lot of friends and talking them with comments daily.
This is true. If you skim through the leader-board then you'll see that most of the people there have many comments. If you want points quickly, then just frequent the tavern. There's a lot of threads in there and you can have decent discussions in there. It also helps if you post in a lot of the sub-forums, but don't spam, because ya know, that could get you banned.
I only joined I'm already the second rank, I try to comment and get to the forums as much as I can!
That's the way but you have a lot of ranks to reach yet and it takes a while to achieve that. And when you play games, rate them and leave a good comment.
Merits are comments that you leave about a game that is constructive and critical (not necessarily in a bad way) so that other people would follow your example. You get them by leaving a comment like what I said above, and also add what you would change and stuff like that. They are worth 25 points, so they are well worth striving to achieve.
Be active on the site! Rate games, post comments on them, participate on the forums, just generally post on the site and give reviews. Points are not things you can rack up easily in a single day, you have to work hard for them and before you know it you'll have a ton.