[@Aristo]

 With regards to the dieties, I suppose it would matter how important would the people of the world find them to be. Do they regard them with high esteem or because they are fickle would their follows be more loose with their piety? This should shape how much influence they have over the mortal coil. So let's assume these deities are having some level of feuds; are the gods capable of harming each other? Or are they damaged only so much as their belief on the mortal plane? For example, if one god is beleived in less than another - is that god less powerful than the other? I would suggest a pantheon of few dieties given their roles may be in the background. If you fear such black and white thinking avoid it. Or take the deities and provide them with a weakness as provided in that, if it is our gods versus your gods the gods must interact and observe their people otherwise they would risk becoming nothing. 

Does this make sense? 

On another hand, I'm not quite sure why you are starting with dieties though. YOu might consider the land mass and how it was developed, the myth of creation. The position of kingdoms, powers, land marks etc. Things that directly influence how the dieties came to be or how they developed span of powers.