Most of the time you spend leveling will involve questing and slaying monsters, but there’s also a lot of travel. Travel earns you little experience (you do gain a bit for discovering new areas), so it’s wise to keep travel to a minimum. The new level scaling system, which scales zones to your level within a preset range, helps with that. You can choose what zones you want to experience and stick with them until you finish their quests.
Drustvar is far and away the hardest Alliance zone, which is exactly why you want to do it first. If you have legendary items, they’ll still be usable, and if you don’t, this zone will still be easier early on than it will be later. Drustvar is also extremely fast and will let you jump out ahead of your competition in other zones, which means fewer players around to take your quest objectives.
The Hearthstone has a cooldown of 30 minutes, but there’s a guild perk called Hasty Hearth that shaves the time by half, giving you a strong incentive to join a guild. Yes, even if it’s some random guild that invites you without warning. It may feel odd to join people you don’t know, but if they have Hasty Hearth (and most guilds do), joining can save you a lot of legwork.