Questing. But thats not all of course. You are probably alerady bored of gays running around and begging for money. Eventhough there are still people who give money to those kind of beggars, its still a waste of time. So, first, what you need is money. I will assume you are an alliance player, since the horde generally doesn't have any problems levelling fast hehe. Whatever, you sure need to level to level 12 following the quests given in your home region. And when doing those, be sure that you loot everything. You run out of free backpack slots in no time, but that is handled easily once you reach your level 6 town in the middle of the start region where you can buy many other bags. So, at first, save up some money for backpacks, because once you get the other puches and shit, you starto earn more money on each delivery, and continue looting everything. Also that your joruneys for quests will take longer between each visit to the town so you ll be looting many more items. And until level 12 do not be afraid of killing all the mobs that attack you. Kill all of them and loot all of them. Be sure that you are level 6 when you arrive the town in the middle of the region and also be sure you are level 12 when you are ready to leave your region.
Continuing as assuming you are still playing an Alliance character. For fast levelling, you need to be safe, which means you need to be somewhere close that most high levelled people are. As instance, westfall instead of darkshore, because theres no one in darnassus or exodar or even that part of the world, of warcraft. So, whatever race you are, head to westfall after level 12. Start doing the quests there with sam philosophy, loot them all- Also be sure that you finish every single quest in an area before you go visit the town to get other quests. Make a ring for your questing. Such as, if you are bound to jasperlode mine, get all the quests about jasperdole mine, and maybe all the qust that are next to jasperdole mine, and next to that. So you do these all in that particular order to make a ring. You travel and do quests non-stop and return to your town. Sell all the loot you have gained, buy better items, also be sure you do not waste money on little improvements but big ones. For example dont buy a boot with +14 armor benefit but a shoulder slot armor if you havent one. Well since you are down to fast levelling, you shouldn't be messing with going for any professions since to keep on track with a profession along with levelling you really do need to pay attention to the profession and give it time, which, on this matter, a waste of time.
It is also important that you turn on your best action music on. The classic wow usic isn't so dragging so you need some action music that you like. So why not James bond? Or lets see, any of horrorist stuff, or that kind of music with a hard and fast beat that you can actually take pleasure even hen you kil simple mobs. It can also be Red hot chili peppers which makes you cy when you are playing. It is a great motivation. Well with all these done you can level fast enough to be the king of the game. So i really hope you follow the tips i have given here, which will certainly take you out of being a stupid noob and take you somewhere. Good luck in h world! -Of warcraft.