I’m a beginner. May I ask how to upgrade quickly?

[Quindiana Jones]

How far in are you? One of the best places (the best place) to train early on is when you get Basch as a guest character. There's a save point about halfway through the dungeon. Near here, if you let the power go down, you can fight a constant stream of undead (the bones they drop get you rich, and they give good exp. Oh, and they drop Iron Helms). And all you have to do is go back two screens and tap the save point if you need healing. I'll go into proper detail if you ask me, but for now I'll leave it at that. It's actually quite easy to miss.

Also, I used Werewolves to train up so that I could take on the (SPOILER)two Demon Walls in Raithwall's Tomb. This gave me a few Kotetsus (I gavethem to my Damage Dealers, and they weren't bested until I reached...that...refugee place. Oh crap, I've forgotten names), and a few Demonsbanes which also weren't bested until a lot further into the game.

There is another great training spot (for low levels) in the Bhujerba Mines which I can describe in detail. I also know a good few for higher level training. Just ask if you need to know anything. Chances are Googling "final fantasy 12 training" will net you some awesome spots too.