You should focus on NLHE and get proficient in the varying forms of it. Get a good grasp on cash games and also MTT's. Focus on playing a better game, not just playing a mediocre game on a multitude of tables.

Then I think it's an easy switch to the other games. Other games have the same concepts just the cards are laid out differently. So if you can master odds, percentages, reads, etc. They all translate into the other games.