Just follow the roads and road signs unless otherwise noted. Also note that these are not ALL the flight points in Northrend, just the ones that help you get from one starting area to the other (and to Dalaran). I used this map with Travel Paths and Names for Locations turned on. It's a good resource.
You might want to set your hearth to Shattrath or Dalaran, unless you're a mage, so you can head to the appropriate second starting area.
- Warsong Outpost
- North: Amber Ledge
- North: Bor'gorok Outpost
- North (optional): River's Heart
- Vengeance Landing
- Northwest: Camp Winterhoof
- Northwest: Conquest Hold
- West: Venomspite
- West: Wyrmrest Temple (between here and next fp is a gorge; you can run just south of it, there's a path)
- West: Agmar's Hammer
- North: Kor'kron Vanguard (Connects to Dalaran)
- Valiance Keep
- North-northwest: Amber Ledge
- Northeast: Fizzcrank Airstrip
- Ironforge --> Menethil Harbor
- Northwest: Westguard Keep
- North: Amberpine Lodge
- West: Wintergarde Keep
- West: Wyrmrest Temple (Connects to Dalaran)
These circuits were completed at level 70 on Dustfire (no deaths) and level 55 on Birdfall (5 deaths, no stealth).