Picking up herbalism and mining is the best professions to have while leveling. Not only will you earn gold as you level, but you will also get extra XP. At level 20 you will get over 500 XP for picking up a ore or a herb while killing a mob only gives a little over 100 XP. Don’t go out of your way to pick herbs if you are trying to level quickly, but pick the ones that are on your way. Leveling from 110 to 120 can be done pretty quickly just by doing this. There are a few items that will help you if you decide to use professions while leveling:
Things like Tauren melee reach being bigger, which is something I experienced going away live during Black Temple Illidan progression (at least for that particular encounter), is confusing to players as it's a significant advantage over other races in some instances. No quest tracking is another apparently confusing issue, as many Mankirk's WIfe seekers well know, and there's a whole lot more where that came from:
Here comes the first stress test for the Classic beta, and Blizzard will be inviting a lot more people this time around. It's taking place this Wednesday, May 22nd and will last for 2 hours from 4-6pm PDT, but the realm itself will be available for a full day. All races and classes will be available, but the max level will be set to 5. Also, current beta testers will not be able to play their beta, but will have to join the new stress realm and make new characters if they want to play.

Darkmoon Faire: The Darkmoon Faire comes around once a month and provides two ways of bonus XP. You can ride the carousel to get the “Whee!” buff (10% bonus XP for one hour). You can also get the Darkmoon Top Hat by playing a few games, which gives you 10% bonus XP but only works during the Darkmoon Faire. Both of these are generally not worth it for the most part, as you spend more time running to get the buff than you gain in XP when leveling.
Even if you don’t have flying in WoD be sure to get the WoD handy notes. If you have flying simply fly and pick up all the treasures that you can and do bonus objectives. Not every single piece of treasure will be worth it though as some are hidden in caves or are just hard to get. So if you find yourself spending more than a few minutes finding a treasure, just skip it and move on, there is plenty of treasure to go around.