I addition to what is posted above.
If you can't find a new task ..... try the following:
- Return to your main camp and see if there is a character you need to talk to.
- Return to 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 must complete.
- Do you need to give the character or do something, such as food, material or other items?
If you still can't find a new task ... check out this link
If you're stuck again, check out Wiki pages, quests, maps, videos, guides, tutorials, and hidden gifts / bonuses.
Personally, I find maps much easier to view, study and follow in specific scenarios.
Mines, Maps & Videos