It is a fact that the primary game in World of Warcraft does not begin until you have reached the very end
. Everything else that is done before that point is done strictly to learn how to play and prepare yourself for the final event.
This is why all players try to get to the highest level as quickly as they can. A lot of factors go into leveling quickly. You need to take the right quests and know which talent tree you should select.
Which talent tree is the most effective?
The warlock is in the pure DPS class. This means that he is excellent at delivering damage to your opponents. So you might think that you simply have to choose a talent tree that is designed for mass carnage. But there is so much more to it than that. Mana efficiency is actually far more important. When you have mana efficiency, you will not have to drink and regenerate nearly as often. "Affliction" is actually the best talent tree to be found.
When you are an Affliction Warlock, you will find that your damage over time spells (or DoTs) are far more effective. When you choose the talents "Soul Siphon" or "Siphon Life", you will find that you have the ability to quickly drain your opponents' health, helping you to defeat them. Meanwhile, you will be able to quickly recover from most attacks. I was able to level up my Warlock without stopping to drink at any time. I leveled up incredibly fast because I never had to stop to recover.
Demonology is also a popular way to level up. However, I found this method to be much slower. It also is not nearly as interesting because your pet is the one actually doing the job. I just didn't find it to be much fun. Finally, you should actually avoid "Destruction" tree when you are trying to level up. It is utterly mana inefficient and you will only lose your nerves by using it.
What about Questing?
This is an excellent way to get the XP you need to level up. However, Blizzard can create so many quests that you will only be slowed down. You will receive a small amount of XP, even though the process requires a great deal of time.