Nubee Question

What's the main difference between quests and missions? I prefer completing one quest before starting another one, is this okay?

Quests are what you pick up from NPCs. You complete them for exp/money/skills. They can be abandoned at any time you are in an outpost/town. You can have as many quests as you want and complete them when you feel like it.

Missions are what you complete to advance in the story. In Prophecies, you can pretty much pick up wherever you want. But in Nightfall/Factions, you have to complete the missions in order to continue with the game. They don't allow you the freedom to choose where you want to start.

To elaborate on that, Missions are started in special mission towns. A party gets together, and then the leader presses a "Enter Mission" button that appears below the party window. Then, the party is transported to an instance for the mission, where the group is given goals to complete, and rewarded in varying levels. In prophecies, completing the main goals will get you 1000xp and a skill point, and completing the special Bonus task (obtained form an NPC somewhere inside the mission) doubles the reward. In Factions, the party earns a Standard, Expert or Master level of completion based on how much time it takes. In Nightfall, the party gets the initial main objectives, and a bonus is added sometime along the way, not necessarily by talking to an NPC. The reward, like Factions, is Standard, Expert or Master, but instead of time it's based on how much of the bonus you do; no bonus at all is Standard, partial completion of the bonus is Expert and full completion is Masters.

It doesn't matter if you do quests before doing mission, but going through the missions first will get you to more areas, skills, items etc. which are very useful Imo.

This is true in Prophecies. PRIMARY quests and missions advance the story-line. In Nightfall and factions, you have to do the Primary quests and missions in order. If you get to a mission town and haven't completed the Primary quest that leads to it (and accepted the reward), you won't be able to enter the mission.