In addition to what gamemaster posted above.
If you can't find a new quest ..... try the following:
- Return to your main camp and see if there is a character you need to talk to.
- Return to the City of Athens to see if there is a character you need to talk to.
- Return to Olympus to see if there is a God you need to talk to.
- Return to the last game scene / mine you worked on to see if there is a character you need to talk to or a task you need to complete.
- Do you need to give something to or make something for a character like food, materials or other items?
If you still can't find a new quest ... check this link
If you get stuck again, check out the relevant Wiki Pages, Quests, Maps, Videos, Guides, Walkthroughs & Hidden Gifts/Bonuses.
Personally, I find the maps much easier to view, study, and follow in specific scenarios.
Mines, Maps & Videos