Shaman Leveling Guide 1-65
World of Warcraft Shaman Leveling Guide - Levels 1-20
Play around in your starting area for the first 20 levels. Do a couple deadmines or Ragefire Chasm runs to get a couple blue or green items. Make some friends for later on down the road.
World of Warcraft Shaman Leveling Guide - Levels 21-30
The tougher parts of the barrens for Horde players, or Redridge Mountains and the Wetlands for Alliance are good transition areas for a shaman. At level 23ish, you can move to Ashenvale, or the western part of the Stonetalon Mountains, if you're on Kalimdor. The Eastern Kingdoms, Wetlands can still be a hub for quests in the mid 20s, as is Duskwood and the Hillsbrad Foothills.
As for instancing, the Wailing Caverns is a good choice for some gear, but for Alliance player's it's harder to get there, since it's deep in the Barrens, which is controlled by the Horde and swarming with players usually. In the late 20s, you can go to Blackfathom Depths (Ashenvale), Shadowfang Keep (Hillsbrad Foothills) or the Stockades (Stormwind, Alliance only). I'd suggest grinding Blackfathom and the Stockades if you're Alliance, because Shadowfang is mostly a clothie's instance and there are less quests there anyway.
World of Warcraft Shaman Leveling Guide - Levels 31-40
Desolace is a good place to go to if you're a leatherworker, while Alterac Mountains or Arathi ar better for miners. Now you have Ravorfen Kraul (32ish) and Razorfen Downs(38ish) and Scarlet Monastery (all the way from 35 to 40). All three are easier to get to if you're Horde, so it's a bit of tough luck for Alliance at this level range and since you don't have a mount yet.
Stranglethorn Vale is awesome level 30+. The Rebel Camp and Nesingwary's Expedition are excellent grinding spots that you should exploit up to around level 36. The Venture Co Base Camp near Lake Nazferiti is also worth checking out, because it's a place where other classes have a harder time grinding.
World of Warcraft Shaman Leveling Guide - Levels 41-50
For starters, at level 40, go to the Hinterlands to Hiri Watha. This is a relatively quiet area with mobs ranging from level 40 to 43 that you can tackle. Hinterlands, although being a contested area, is usually not very populated, so if you're the type that simply wants to powerlevel with no one bothering you, then this is the place to be at, for around 1 or 2 levels. The Scarlet Monastery Cathedral can be tackled now and so is Uldaman. I'd wait until level 44 for Uldaman though and get through levels 42 and 43 by either grinding the Naga Explorers in Southern STV, or the Waterspring Humanoids in Tanaris (they're level 43-45, easy to kill and have good drops).
Levels 46 and 47 can be filled with a couple of Uldaman runs, a trip to Azshara if you like the seaside (Haldarr Encampment), or the Feral Scar Vale in Feralas. Tanaris, Azshara and Feralas are my favorite picks. Tanaris has a lot of nice quests and is quite compact, plus it has humanoid mobs with good loot. Azshara is quiet with little player activity, plus the mobs there drop like flies.
Lastly, for levels 47 to 50, Zul Farak is an important source of gear and experience and you can also grind the Searing Gorge (very compact, humanoids, good quests). The Southmoon Ruins in Tanaris are grindable, with mobs ranging from 47 to 49.
World of Warcraft Shaman Leveling Guide - Levels 51-58
Three areas work great in the 51-53 range: the furbolg villages in Felwood, Sorrow Hill in Western Plaguelands and the Frostfire Hotsprings in Winterspring. Felwood and Winterspring are a good combination and you'll also get some nice drops there, plus the rep if you're aiming for the rewards. Ungoro Crater is my favorite area for 53-55 although rogues have a great advantage here, as they'll be able to avoid the patrolling mobs better than any other class. Sunken Temple should be grinded a couple of times if you're aiming for some specific gear, but don't overdo it, there are several places where you can get a better experience/hour ratio. Such as the Blackrock Stronghold in the Burning Steppes. Blackrock Stronghold was loosely considered the bestgrinding spot pre-TBC, but now you should just use it as an experience well to get to 58 and step through the Dark Portal.
World of Warcraft Shaman Leveling Guide - Outland
Stepping to Outland doesn't really change much in terms of how you should collect and use gear. Sometimes it's faster to jump from mob to mob if you have the Stamina for it, than killing mobs faster due to the higher AP, but having to downtime a lot.
If you've quit World of Warcraft before The Burning Crusade and just came back, remember that your gear value perception will be a little bit off, if you've been playing at 60 for a long time.
World of Warcraft Shaman Leveling Guide - Levels 58 and 59
One thing that Outland has in abundance is quests and despite the fact that you could find grinding spots that offered you better experience than questing so far, in Outland it's an absolute must to combine grinding with questing if you're to level quickly. Most quests in the Hellfire Peninsula are clustered in specific regions, so do a sweep of both camps there and collect all possible quests, to save you some time (note that the western part of the Peninsula is higher level, but you can still get to the camps if you make a run for it).
Come back to the Eastern part and complete the "local" quests there while grinding the level 58 mobs when possible. Remember that Outland mobs give you almost twice as much experience as mobs of the same level in Azeroth. So from now on, try to stay in Outland for the majority of time, there's no use grinding or questing in Azeroth anymore.
World of Warcraft Shaman Leveling Guide - Levels 60-61
You have one of two options at this level range to speed up your experience gain. The first one is grinding and questing in Eastern and Central Hellfire, which is definitely the fastest way to get experience. However, you can also grind the two instances in the Hellfire Citadel, the Ramparts and the Blood Furnace. You may make less experience per hour, depending on the party you hang with, but it's definitely a good way to replace your Azeroth gear, which will speed up grinding for the next 2 levels. Entirely your call really and it might also depend on whether this is your first char through Outland or not. If it is, I suggest you take it slower and get a combination of questing and instancing done, but if you're just speeding through the levels to get your shaman to raiding capabilities, go for the questing + grinding combo.
If you skipped some of the quests in Hellfire and went on to Zangarmarsh, a great grind spot is in the Dead Mire, straight up as you enter. Admittedly, this place seems to always be crawling with players, but if you're lucky enough to catch them resting, you can get an impressive amount of experience and money from the Bog lords there. They drop Motes of Life quite often and you'll need loads of them if you're a Leatherworker.
World of Warcraft Shaman Leveling Guide - Levels 62-63
Another two-option choice. You can either jump to Terrokaar Forest, a new great quest hub, or continue to instance in Hellfire and Zangarmarsh until you hit level 64. As a shaman, Terrokaar was pretty sweet, it reminded me of STV a bit :) I've also been to Zangarmarsh with my priest and had a hard time, getting owned in the naga camps and by those silly tribsemen. But if you don't like the area, just finish all the quests in Hellfire and get to level 63, then skip directly to Terrokaar. Make sure you go to Shattrath and take the flight path of course.
World of Warcraft Shaman Leveling Guide - Levels 64-65
This is the perfect level range to tackle the instances in Zangarmarsh (Slave Pens and Underbog) and the first one in Terrokaar, the Auchenai Crypts. After you've reached 64, I would advise you to jump straight to Nagrand. It's a cash cow out there and it's time to start gathering some gold for that new mount. There are 2 great places to grind for money and experience in Nagrand. The first one is the Elemental Plateau in the Northeast. You'll tackle level 65-66 mobs that aren't too hard to kill and that drop motes of fire and air on the edges of the valley you can get motes of earth (but these are less profitable and the earth mobs are annoying). The main problem in the Plateau is not the mobs, their number or their difficulty, it's the amount of players that see this area as a money making opportunity and constantly grind it.
The second place to grind is the lake near the Throne of Elements, at the foot of the mountain holding the Elemental Plateau. Less player activity, but you'll fight underwater mostly, which is always a nuisance. Motes of water drop pretty well, however the mobs are scarcer. So it's really more of a money-making grind spot than one for leveling.