This is also the reason why when I read in WoW forums of people skipping guide sections, due to being too low level I'm not agree and start ranting about it: it'll be a mess syncronizing with the guide and I've seen many people complaining about missing quests or accusing the guide for being innacurate, but not realizing that was their fault since they're skipping and missing a lot of quest chain requirement. Of course this apply if you're following a guide, believe me, it's very frustrating when you remain stuck in a guide section due to the reasons I've mentioned, more than doing grey quests (but they allow to be perfectly in sync with the guide) and goiing here and there to get the pre-requisite quests.
Certain locations in World of Warcraft – primarily inns, capital cities, and private instanced zones like your garrison or class order hall – are rest areas. You know you’ve entered one because your character portrait will gain a “Zzz” icon where your level is normally shown, and because you can immediately log out of the game instead of waiting 20 seconds.
Note that these general principles do not apply to blue or purple items. If you are a first-time player, there is absolutely no reason to purchase these items. None. Sub-80 rare and epic items are only for the alts or twinks of established players that have money to waste (because that's what it is) by showing off their Staff of Jordan (or whatever). Blues and purples are completely cost-ineffective for first-time characters. Within a few levels, you will find green gear that is roughly comparable, or you'll get better blues from instance runs at the same level. So, do not buy these items, under any circumstances, if you are a first-time character (no matter how cool they look). And even if you're reasonably well-off financially, think twice. This is especially true as your character gets closer to levels 58 and 68. Even the most basic quest-reward gear in Outland will have substantially better stats than anything you can buy off the AH for a level 56 character. The same is true of Northrend gear at level 68 vis-a-vis the stuff you'll get in Outland at level 68. As such, smart players stop making AH gear purchases by about level 54 or so, and then just gut it out until level 58. The same is true at levels 64-68. Within the first several quests in Hellfire and/or Northrend you'll have replaced half of your gear in any case, guaranteed.