Okay, I've played through not a lot of the game, just back from the first mission and Squalls levelled up 6 times so far...

I knew that enemies got harder as you levelled up, and I though I was prepared for it...
Then I saw i nanother topic where someone said they didnt level up ONCE in the entire game (except Irvine leveling up once) How do you do that?
How do you stop characters levelling up?