1. Start in Twinleaf Town: Begin your journey from Twinleaf Town.
2. Route 201: Head east from Twinleaf Town onto Route 201.
3. Jubilife City: Follow the path and you'll reach Jubilife City, the first major city in the game.
4. Route 202: Leave Jubilife City and head south onto Route 202.
5. Oreburgh Gate: You'll encounter the Oreburgh Gate, the entrance to Oreburgh Mine.
6. Oreburgh Mine: Enter the mine and complete the challenges inside.
7. Oreburgh City: Exit the mine and you'll arrive at Oreburgh City.
8. Route 203: Leave Oreburgh City and head east onto Route 203.
9. Eterna Forest: Follow the path and you'll enter Eterna Forest.
10. Eterna City: Exit Eterna Forest and you'll finally reach Eterna City!
Important Notes:
* Gym Leader: Eterna City is home to the second Gym Leader, Gardenia.
* Training: Make sure to train your Pokemon as you travel through the routes, as the Gym Leader will be significantly stronger than the trainers you've faced so far.
Let me know if you need help with anything else in your Pokemon Diamond adventure!