Having made a small number of posts about how different classes work, I realize that how one goes from class to class is a bit unclear. This post should make things a bit clearer for everyone. The progression from Warrior to Dragoon will serve as an example.
Class Level Progression: The current class system has each tier spanning 10 levels.
(1-10 for Warrior, Spearman 11-20, and Dragoon 21-30)
When a character reaches a level benchmark (10 or 20). A notification will occur, informing the player that a character is ready to be trained in a new class. At this point, a class trainer needs to be found and spoken with. Also, any further EXP gains will be reduced to 0 for that character.
Qualifying for a Class: Unlocking a more advanced class will be a function of finding a class trainer for the class you want unlocked, and performing a task for them. There are no other requirements than that.
Hybrid Classes: Hybrid classes, such as the Paladin, will not require a certain number of levels in both related classes in the lower tier. Warriors and Clerics will each have their own version of the Paladin that will be assigned.
Training: Upon speaking with a class trainer, you are given options for which class to train in. Each trainer will have a set list of classes that they can train. This decision is currently irreversible, but that may change in the future.
New Skills/Spells: Once the new class has been assigned, EXP gains will return to normal. Upon reaching level 11, the first skill/spell for the new class will be granted.
If you have any questions or comments, feel free to use the form below, and I will respond as soon as I can.