Not much yet, but...
I should put the speech about skills that was on the old skills page here... I'll just type out something similar...
What Skills Are:
Skills are special abilities that your character can learn using JEXP (Job Experience). Their effects range from increasing stats to making you invisible. Skills are generally categorized into two types: Active and Passive skills. Active skills are skills that make you do an action. Passive skills are skills that give effects just by learning them. An example of an active skill in Avabel Online is the Creator skill 'Wield Blow.' Using this skill causes your character to deliver a three-hit combo. An example of a passive skill would be the Acolyte skill 'Repose Mind.' This skill increases your SP recovery rate. You do not need to 'use' Repose Mind in order to increase your SP recovery rate. You simply need to learn it and it will take effect automatically.
Limitations:
Before you can use any skill, you first need to learn it. This requires JEXP. JEXP is gained by killing monsters and completing certain achievements. In general, stronger skills require more JEXP to learn and level up. There are no limits to passive skills except that you need to learn them before they take effect. For active skills, on top of the requirement that you need to learn them, you need to have enough SP to use them. All active skills have a set SP cost.
Variation:
So in case you were wondering about the variation in skills... You'll probably end up using the same two or three skills all the time. At level 6, most (if not all) active skills branch out into one of three types, labeled A, B, and C. They are all generally the same skill, but they have slight differences that may change the way you use them completely.
Note: All damage multipliers are approximations. I'm still not certain how damage is calculated, so the damage multipliers are a bit iffy right now.