Well commenting on friends pages gets you 2 AP per comment along with commenting on games.You could try that,but I wouldn't worry about it too much.Right now I'm just letting my AP go up at its own pace.
Merits are tough to get though. People just could give up and don't waste time on there comments.
It's not that hard to write a paragraph about what you don't like and like about a game o_o -- But AP is for fun, don't focus too hard on getting it, otherwise you're going to find yourself hating the work it takes to get those points Xo