At Level 22, you unlock Aspect of the Cheetah which is a movement cooldown. It increases your movement speed by 90% for 3 seconds, and then by 30% for another 9 seconds, on a 3-minute cooldown. Note that it does not stack with the Posthaste Level 45 talent, so you should make sure to use Disengage and Aspect of the Cheetah separately for movement.
1. Don't just take anybody with some gold willing to go. Make sure they at least have some heroic gear or better. Bringing someone in greens not only hurts your chances of killing the bosses, but these players often anger those who are in better gear that need one item and then get outbid by some "noob". You are looking again to establish relationships and repeat customers!
Game director Ion Hazzikostas told Kotaku that the team plans on turning every one of the game's servers into PvP servers. However, everyone will need to opt-in to PvP combat if they wish to participate in battle. The catch is that players will only be able to turn PvP on or off inside of major cities. Out in the wild, you'll live with the decision you've made. 
Once again, as soon as you hit 70 - I recommend to go and learn faster flying. This speeds up your questing A LOT, and is worth the time and gold. It will cost 4500 if you go to the capitol, or 5000 if you prefer Shattrath/Dalaran, because you will not have reputation with them at that point. This price will sadly be above what a totally new character can afford, if you don't have any Main. But you should go and buy flying as soon as you have enough money.

Always post a buyout price on your auctions. Don't think that "They'll just bid it up anyway." Many players will not bid on an auction with no buyout price unless the item's bid price is heavily discounted to begin with. This can lead to bidding wars, but in many cases the item will sell for a fraction of what you could have gotten if you had posted a buyout price in the first place. You will have more sales at a higher price and get your money more quickly if you post a proper buyout price.

EXCEPTION: If you are leveling trade skills while advancing, review the materials requirements of every recipe, pattern, plan, or formula that are planning on purchasing from a trainer. For example, some of the shirt patterns for tailors use very few materials and thus yield a more efficient manner of leveling the trade skill. Check profession leveling guides here on the wiki, ask a guild-mate or friend, or check out information on other web sites to help in this area. A little pre-planning and fore-thought can save you huge investment costs in the long run.
Once you have your finished product and have a price for it, keep in mind that using either your faction AH or the neutral AH also costs money: if the item does not sell, its deposit is taken by the AH; if it does sell, the deposit is returned, but a cut from the payment it taken by the AH as a commission. You must factor this into your selling price: your faction's AH will take 5% from your sale, while the neutral ones will take 15%. You can factor this into your cost to determine the minimum price at which you need to sell to at least break even:
For this farm we're taking it all the way back to eastern kingdoms.  We're going to be killing the purespring elementals in the purespring cavern for the item essence of water.  Essence of water is a semi-rare drop that goes for a shocking 252g per piece.  The caveat is that it doesn't drop all too often, but is still worth the trouble.  I wasn't getting TOO many of these, but I was still making bank with them.  The essences are used to create the old-world illusions, so they do have some inherent value.  Simply patrol the area and kill as many elementals as your heart desires.  It's a really cool and fun farm that can be done on autopilot.  Usually there is noone patrolling the spot.
If i start on a new realms, I am farming a lot of transmog from classic and Burning Crusade Dungeons and Raids. In the beginning, i start to post them if they have at least a DBRegionMarketAvg (Average value of an item on all EU realms of the last 14 days) of 500 Gold. All the other items get vendored. The time you hit a stock of 1000 Items, my value treshold raises to around 2.500 Gold. All the items below that value get vendored aswell. Newly farmed items that are above these treshold will be listed. Why? If I start over somewhere, I want to get a certain amount of gold quickly. Cheap items are great for that. Later on, to save time, Quality is better than quantity. As mentioned above, re-posting the items on the auction house takes quite a bit of time. At this point, I can recommend you the TradeSkillMaster AddOn, it makes your auction house work really a hell of a lot easier.