In case you find yourself in the New World without a quest to complete, it´s necessary to check the Amazonia or the City of Gods.
When playing the pc version of the game, please go to Map Manager and you´ll see the Amazonia instantly.

In case you didn´t find the new quest in the Amazonia, it´s necessary to look in the City of Gods. Please click on the Main tab and you´ll be able to access the City of Gods from there.

The interface for the app version is a bit different, however, the idea is the same. In case you´re not able to continue in the game and you need more quests, first, check the City by tapping on the city icon:

In case you won´t find a new quest in the city, please go to Map Manager, tab New World and check the City of Gods.
It´s located among the first locations of the New World, therefore, in case you´re further in the game, you might need to swipe to the right a bit. The icon of the City of Gods is different than the others so it should be easy to recognize it.

Hopefully, this will help you guys 🙂 Good luck!
In case you´re having issues finding a new quest in Egypt, please check this article.
If you´re having issues finding new quests in Scandinavia, please see this.
In order to find more quests in China, please look for a piece of advice here.
To be able to get more quests in Atlantis, make sure to visit this link.
In order to get more quest in Greece, please check the following article.