While not 100%, quality of character sheets and writing ability go hand in hand. Most who have high levels of writing ability tend to be good at making characters of similar quality. Thankfully, the majority of those who meta-game, godmod or the dozen other such things do it out of ignorance or lack of thinking rather than doing it intentionally and with foreknowledge that it is as bad as it is.

In the RP we're running, we have several levels of knowledge. Most of the players have some secrets known only by a few (typically the player + GMs), while the player characters also have lots of things in their sheets that the players may know but the characters probably don't know.

With those levels of knowledge in mind, the more serious levels of meta-gaming are avoided simply by most players not knowing others deepest secrets. But the best way to prevent it in our opinion is to have a good group that talks together and communicates. Breed the right attitude in the players, and you avoid it.