Guide key:
H*A = Contested zone
H = Horde zone
A = Alliance zone
I = Zone has a instance
Note: This guide dates from days of the level 60 cap. The info is still Ok if you have to grind your levels, but questing is far superior. This guide will not be updated. See our 1-80 Leveling Guides page for a far superior way to go.
Level 1-12:Just do the quests in the starting area's to hit 10 and if you start as something other then undead go to the undead area for some more quests to hit 12.
Level 12-20: The Barren's will be your home for these levels it can get boring but forge on soon it should be more interesting.
Grinding Spots:
Level 10-13 Area surrounding crossroads
Level 12-15 Bristlebacks in camps around mountain to north of crossroads
Level 13-16 Pirates south of ratchet
Level 16-20 Marines at the keep south of ratchet
Level 18-24 Bristlebacks near Camp Taraujo
Level 17-23 Monsters/animals around Camp Taraujo
Level 20-30: The Barren's will still have some stuff for you to do at this level till about 23-24 or so, and also you can go to the Wailing Caverns (http://www.gotwarcraft.com/guides/wailing_caverns.php) for some xp and loot. H/I
Another area starting about 23-24 or so is Ashenvale you can stay here till about 30. H*A/I
Grinding Spots:
Level 27-31 Saytr at all the Saytr camps along the road going past Splintertree Post
Level 23-26 Monsters around Splintertree post should be good for these levels
Level 26-28 Night elf warriors near various outposts
And also at about level 24-26 you can go to Thousand Needles and level up there till about 30. H*A
Grinding Spots:
Level 26-31 Centaur near Freewind post
And the last leveling zone is the Tarren Mill/Hillsbrad area you can stay here till 28 or so. H*A
Level 22-25 Human's at hillsbrad farms
Level 22-26 Animals/monsters around tarren mill
Level 25-28 Humans in the Azureload mine
Level 30-40: You can go to Stranglethorne Vale at lvl 30 but beware lot's and i mean lots of ganking goes on around here so it might be best to wait till 35+. H*A
Grinding Spots:
Level 30-38 Killing the panthers/tigers is a pretty good way to level up in Stranglethorn Vale(STV)
Level 34-38 Trolls in the various ruins scattered around STV can take you through these levels
Level 36-39 The Goblins at the factory(it's pretty hard