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.
I wouldn't buy Zygor guides. As a player since path 1.10 (around 7 years now) Ive seen a hearty wow community flourish through each expansion. I am a huge fan of the add on, Carbonite quest. It provides a pumped up version of wow's internal quest database. Also, its recommended to research your servers economy for making gold. http://www.powerwordgold.net/ is a great site for tricks of making gold. Pair it up with http://www.theunderminejournal.com and you'll be on your way to making fast gold to provide for all them alts :P