Instructions
Play mini-games often. This is particularly important early in the game, when it is easier to level up. Mini-games were introduced in "Yu-Gi-Oh! Tag Force 2" and can be accessed by speaking with researchers throughout the game.
Duel often to collect cards and unlock booster packs at the card shop. The card shop is located at the academy, which you can access via the world map. When you highlight the academy, you have options of different places to visit on campus; the card shop will be one of the options.
Build a powerful deck. How you build your deck depends wholly on your style of dueling. You can have a balanced deck, or build one that favors monsters over traps or vice versa. Experiment with different deck configurations until you find one that works for you.
Duel the main characters of "Yu-Gi-Oh! GX." Since the game is based on the series, there are tons of characters from the series in the game. Dueling the main characters, such as Alexis Rhodes, Syrus Truesdale, Chazz Princeton and Bastion Misawa, rewards you with the highest amount of experience points.