Don't worry too much about skill builds before the final job change. You get a scroll which resets your skills when you change job, which happens every twenty (20) levels. Skill points can be brought over to your second job, so after resetting your skills, you can put all your skill points from your previous job into your new job. Do take into consideration that there are level requirements for most skills and when you first change job you might not have many skills you can use to add your points into.
This in mind, the following topics will help clarify the ideology behind certain builds.
CC and DPS
Active abilities will fall into these two categories, and can sometimes fall into both to some degree or another.
Crowd Control (CC) is the act of preventing an enemy from being able to take action against you. Damage Per Second (DPS) is fairly self explanatory, as it is the act of doing damage, often measured in damage caused per second of combat.
Most abilities do both at the same time, while some focus more on one or another. For instance, launching abilities do damage, but the amount of damage may not be very big in comparison to other abilities. Learning to balance which CC and which DPS skills you select to use and level is key to maximizing your effectiveness in a given context.
Solo vs. Group Play
Solo game play and the expectations that come with it can be very different from group gameplay, so make sure to consider what you will be doing more of and in which context you wish to get the best performance.
For instance, when playing alone in either PvE or PvP, CC moves allow your character to spend more time in combat and less time trying to avoid damage while your recovery items take effect. While you will likely not do as much damage overall, your survivability has greatly increased.
Contrast this with playing in a group, where party members are also involved, and consideration must be taken with regard to some abilities that are very selective in their targets. Performing unneccesary CC can cause wasted mana and cooldowns as players try to target mobs with their abilities, only to find that by the time the ability can take effect, the condition of the mob prevents their ability from being useful.
Max Leveling Skills vs. Only Meeting Prerequisites
When putting points into an ability, thought should be put into whether the ability is needed to be ranked to a higher level or if you only need a few ranks in the skill to unlock a prerequisite. Because only a few rank of a prerequisite ability is required to unlock the next skill linked to it, you may decide not to level that ability any further.
The point is to keep in mind that you do not need to be afraid to have abilities which are not at maximum level. In many cases, based on your situation, you may find that you allocate skill points into one rank of many skills to get access to a more useful skill further down in a skill tree.