How to set field values when creating new node with Rules? We can create new nodes using Rules Actions. However, when creating new nodes, if we want to set the fields' values for the new node, there seems to be no way to do that in Rules.

E.g. I want to create a new node, using Rules Action, which has a field field_age. And I want to set it to some value depending upon the event. How do I do this? 

Can this be done using Rules?
Yes you can.

Add action: Create a new entity >> select your content type

Add action: Set A Data Value and for data selector use, for example if want to set a value for the body then you use: entity-created:body 

In your case entity-created:field-age

Add action: Save Entity >> entity-created