How To Level Fast In Wow Tip #1: Get a level 1 bank character.
Make a level 1 character and bring him to the closest Auction House City. This will help greatly with leveling your main character. Let me explain why: You'll mail everything your main character doesn't need to the bank char so you don't waste precious leveling time in the auction house, trying to sell your things. Instead, use that time to do quests. Go to Capital Cities every 2 levels to acquire new skills. The bank character should handle everything else there.
How To Level Fast In Wow Tip #1: Get two gathering professions.
World of Warcraft has three gathering professions: Mining, Herbalism and Skinning. I suggest going with Mining and Herbalism, even if you cannot track them both at the same time. Put "Track Mining" on mousewheelup and "Track Herbalism" on mousewheeldown then switch as often as you want. Herbs and Veins are almost everywhere, but skinnable creatures not. Wasting time to find, kill and skin creatures (to raise your skill) slows down your leveling speed considerably. As usual, send all your ores/herbs to your bank character and watch the money pile up.
How To Level Fast In Wow Tip #1: Get a PvE / Grinding Spec.
When leveling you should ignore pvp, healing or tanking specs. Stick to a 'kill fast with close to no downtime' build. Rogues should go combat, warriors arms, priests shadow, warlocks demonology or affliction, hunters beastmastery and so on. It's annoying and slow to level as a protection warrior or as a holy priest. Use 's talent calculator to plan your talents in advance: the best on the market, in my opinion.
How To Level Fast In Wow Tip #1: Instances, Battlegrounds - DON'T.
Ignore the following when leveling: hard group quests, instances with newbie team-mates, battlegrounds, engaging in pvp warfare against griefers and teams of enemy combatants!
They will slow down your leveling time considerably. Stick to one-man quests which involve killing, looting, collecting; ignore quests which send you across the continent or to the other continent!
Try to group quests in the same area. Don't run like a crow who just got struck in the head with the hammer, running all over the map for 1 quest then running some more for another quest. Try to keep quests organized!
Enable the auto-loot option (hit escape -> options menu).
Get some cash early on from selling copper ore and linen cloth to get buy netherweave cloth. Ask a friendly tailor on the chat channel to fashion 2-3 netherweave bags for you so you won't have trouble with bag space.
I managed to get 400g at level 20. It's possible. Send everything to the bank character, sell everything on AH, disenchant every low-level bind on equip item etc.
There's more to say but pfft, the space here is limited. I learned all these tips the hard way (going from Thousand Needles, Shimmering Flats to Stranglethorn Vale and back wasn't a nice experience, I tell you - all this for a lowbie goblin quest).