As mentioned above. I'll be more explicit though:
As a Night Elf, you start near the village of Aldrassil in Shadowglen. You need to leave Shadowglen down the road to the south, follow it as it bends west through the town of Dolanaar, and proceed all the way to the west into Darnassus.
In Darnassus, go straight ahead toward the bear tree on the island by itself. That's the bank. Go around the bank and on to the next island with the pink glowing teleporter. Run through it and you will be in Rut'theran "Village". Down by the water is a dock where the boat to Auberdine harbors.
Get on the boat to Auberdine when it arrives, and when it moors at Auberdine, run straight across to the pier on the other side of the dock and wait for the other boat. This one goes to Menethil Harbor in the Wetlands.
When you land in Wetlands, you will be in for the hard part of your journey. I'd link you a picture of the Wetlands map, but curiously I seem to be lacking one. I'll fix this shortly. Put simply though, there is a big long road from the far west (where you are) to about 2/3 of the way east, where it turns south to the bottom of the map. There is another road that forks off to the north, but you want the east/south road. This area is HOSTILE. Stay on the road, and you won't get attacked *much*, but you might have to make a corpse run or two. Don't let that dismay you.
When you get to the end of the road, you will enter Dun Algaz, a combination of tunnels and upward mountain paths. Just run straight through it. There is a section where there are orcs, but you should hopefully be able to ignore them.
Dun Algaz ends in Loch Modan. The road, again going south, has two forks to the west, both of which go through mountain passes to Dun Morogh. Either is fine to use. If you take the first one, you'll end up running south in Dun Morogh instead. You do want to go to Dun Morogh, either way.
When the north path meets it, the south road is already going east to west. Stay going west for over half the length of the zone, and you will eventually pass Steelgrill's Depot and Kharanos on the left. Shortly after this, the road will turn north and the ramp up into Ironforge will be on the right side soon after.
Ironforge is the home of the dwarves. They however start on the other side of Kharanos, which may make a better meeting point for a gnome or a dwarf.
If your goal is the human lands, go into Ironforge. It is a gigantic wheel. You enter it at 8 o'clock. Tinkertown is the gnome area, at 3 o'clock. There is a tunnel in Tinkertown by the mailbox that goes into a blue swirly area that is for the Deeprun Tram. This is the dwarven subway that goes to Stormwind, the capital of the humans. Use the city map to guide yourself out of Stormwind and down the first road, and you will be in Goldshire, the human equivalent of Dolanaar or Kharanos.
Simple, eh?
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