The class system works a little differently in Aion than in many other online roleplaying games. A player can choose between four different class archetypes, which are the Mage, the Warrior, the Priest, and the Scout. Each one of these archetypes divides into two subclasses at level 10. The Cleric is a subclass of the Priest archetype (the other choice being The Chanter), so for the first ten levels of the game you'll be playing a Priest and not the Cleric in specific. This archetype will give you an idea of the various skills and abilities that will later be available to the more advanced subclasses, in theory to help you choose which play style you are more interested in. This section will guide you through the first ten levels as the common Priest, to help you reach Ascension faster and become a Cleric quickly.
Elyos Priests will spend these levels in the starting area of Poeta, while Asmodians will be in Ishalgen. Characters will generally be able to purchase books to learn new skills at every new odd level, as well as at Level 10 once they have ascended and chosen a subprofession. In general, the quests in Poeta and Ishalgen mirror each other, being similar in what needs to be done to complete them.
The lore is a little different for each race, and there are some different quests as well. The quests in these areas flow very well, and are generally quite easy to follow. After a couple of quests at each "hub", characters will recieve a quest to head on to another area, and on the way to the next questing spot there are often a couple new quests to complete. If you just collect all the quests at an area that you can and then complete the chains, it's very simple to make it through all the areas quickly without criss-crossing the starting area too much. Poeta and Ishalgen also don't have specifically labeled group quests (although having another character around doesn't hurt) so it is also easy to solo quest through the entire area.