The secret to a successful built often lies in the Stat bonuses for the job classes. Swordsman, for instance, gets bonus points for STR, DEX and VIT ; it's a good idea to try sticking with that if it's your first time with the class.
Oh and one last thing - if you're looking even further into classes (this is the 2nd job class) it's also important to watch out for their Stat bonuses as well since they could change from the previous class. 2-2 classes (Monk, Crusader, Bard etc) in particular do this.
While the stat bonuses may assist you as a general guideline if you're that desperate, they're by no means the "secret to a successful build". In constructing an optimal build, job bonuses simply act as another piece of the puzzle.
A culture's teachings, and most importantly, the nature of its people, achieve definition in conflict. They find themselves...or find themselves lacking.