As you're leveling, I generally recommend you just follow the natural flow of the progression through each zone. They're laid out fairly reasonably. But don't be afraid to hop around, especially if you're near a quest objective. You shouldn't actually need ALL of the zones listed to reach 62. Pick the ones you like best. It's much more important to simply be as focused as possible and flow from one quest to the next.
The leveling guides on my site are essentially speed leveling guides. My leveling guides are the same guides I use myself to speedrun to 60 on new servers to get 60 server first. I list many occasions where I tell the player to "die on purpose" to go faster. I tell the player to skip certain quests, because some quests are just not worth the time/XP. I list tricks and shortcuts to go faster so you can reach level 60 much quicker. I am still constantly going through them over and over again perfecting the guides to make them faster and easier to follow. For the most part, the guide can be followed without the need from other player's help, as the whole guide was made from a solo run anyways. Although I do list quests that can optionally be done if you have a group.
Elixirs serve the same purpose as Flasks, but the buff expires if you die. You'll only use these between 1-70, generally speaking, until you can start buying Flasks which persist through death. Try not to die, and carry extras just in case. If you can't find an Elixir with the stat you want, look under scrolls, since they count as battle or guardian buffs as well.
It's not an enchantment, but you should buy or craft an iLVL 100+ belt, gloves, or boots with a gem socket for use with the new 5% bonus experience gem: Insightful Rubellite. I used a vendor-bought belt from the legacy valor vendor in Orgrimmar, since it was convenient and met the minimum ilvl bonus. Keep these in your bags until you can equip them, which should be just in time for treasure collections in WoD content. I didn't ever replace the belt until I dinged 110, since I didn't feel the stats from later upgraded belt drops made enough of a difference to outweigh the 5% bonus. This is explained below, in the WoD treasure section.
Baelgun - Alliance Baelgun - Horde Balnazzar - Alliance Balnazzar - Horde Blackhand - Alliance Blackhand - Horde Blackmoore - Alliance Blackmoore - Horde Blackrock - Alliance Blackrock - Horde Blackscar - Alliance Blackscar - Horde Bloodfeather - Alliance Bloodfeather - Horde Bloodhoof - Alliance Bloodhoof - Horde Bloodscalp - Alliance Bloodscalp - Horde Blutkessel - Alliance Blutkessel - Horde Boulderfist - Alliance Boulderfist - Horde Bronze Dragonflight - Al... Bronze Dragonflight - Horde Bronzebeard - Alliance Bronzebeard - Horde Burning Blade - Alliance Burning Blade - Horde Burning Legion - Alliance Burning Legion - Horde Burning Steppes - Alliance Burning Steppes - Horde Bladefist - Alliance Bladefist - Horde Blade's Edge - Alliance Blade's Edge - Horde Booty Bay - Alliance Booty Bay - Horde Borean Tundra - Alliance Borean Tundra - Horde
There are several reasons why this may have happened. First, only a fraction of the players who interact with the auction house buy or sell WoW Tokens. While the value of both gold and commodities plunged relative to real money, the value of gold and commodities remained steady relative to each other. Players who didn’t interact with the Token market could buy the same number of flasks by doing the same amount of world quests, or selling the same number of gems or enchantments, so these sellers saw no reason to raise their prices.
These two expansions are virtually identical in terms of exp/h. I personally favor Mount Hyjal, and think it's very slightly faster. But if you know Jade Forest well you can just as easily keep up there. Ultimately you'll end up doing both anyway, so it's mostly academic. Every time I've tested Valley of Four Winds or Deepholme, or any other zone in MOP/CATA's level range, they were worse exp/h. You should not even need to complete both zones to ding 91, so it's more important to just pick one and go.
Once characters reach the level cap, gameplay turns from leveling to the end-game. This represents the culmination of the leveling process and the beginning of the deeper challenges awaiting max-level characters. While play prior to this point is oriented around accumulating experience and gaining new skills, the end-game represents the polished 'final destination' for players, at which characters are fully developed and ready to tackle the biggest challenges in the game, or to relax and make their own adventure.