For WorldWinner, I have to admit that it can be difficult to be profitable over the course of playing numerous games on there. Other than getting "lucky" and being able to put up a high score against players who didn't perform as well in a high stakes game, you just have to know when to back off from playing when your rank gets too high. It seems to me that the ranking system on WorldWinner is very elastic, whereby you can hit the top ranks relatively quickly with a streak of wins.
Also, yeah -- playing those 36 player cash games kind of helps your odds with being profitable if you're able to put up a good score in game on a somewhat consistent basis.
Jacob, aka Meikyousisui on King.com & Worldwinner.com