According to the Robin Torres, we know some Dos and Don'ts to help you get some speedy leveling done before Launch Day. Here is the list, please learn from this.
Don't pug instances
Completing instances with good groups can be a great way to level up and get appropriate gear for easier questing. Running instances with pugs are most likely to be time consuming, frustrating experiences that will take up all of your play sessions and then some. There are plenty of quests that can be soloed from 1 to 70 and that way you are the master of your own time.
Don't go AFK in contested areas on PvP servers
Captain Obvious says, "Duh!" Of course, we casual players are well aware that real life interferes when we least expect it and the resulting deaths just can't be helped. If you can, however, try to get to a safe place before going AFK or else expect to face a scene similar to the one pictured above.
Don't worry about revenge
During the lazy days of summer, logging off to get your main and thump the twerp who just thumped you can be fun and rewarding, in an eye for an eye kind of way. But now that Wrath is almost upon us, if you really want to level quickly, it's best to just brush yourself off and continue with your questing.
Don't sweat the deadline
If you have played any MMO from the beginning or this isn't your first expansion, then you already know that the first few days are always rocky. Even if the developers have done their job perfectly and the hardware works without a hitch, there will still be dozens of people in every immediately accessible new area. They will be lagging the same zones, camping the same spawns and gathering the same resources. Do you really want to be hanging out in the DK starting area listening to the ramblings of Dkpwnsu, Dethknyte and Arrrthess? Waiting a day or two for the masses to race through will probably enhance the quality of your playtime quite a bit.
Do read leveling guides
WoW Insider has some great leveling guides for each class. These guides have collected everything special your class can do and should know for specific level ranges. You will often find me enthusing about Jame's leveling guides as well, particularly his Horde one. The maps and efficient quest groupings make this guide invaluable to the casual player.
