A few thoughts before work takes me over for the day.
Definitely wait for the Lore to comes out. My approach is to also talk to all the NPC to get a feel for things. Example:
For instance I have a character that is an Elshimo Mithra from Khazam and I noticed that the priest there called them heathens and was there to convert which severl resident mithra didn't like. Then I looked other things up and saw that the mithra there were basically a tribal culture that worshiped nature spirits, aka the avataars, and gave offerings to Ifrit. All other indications reminded me of Native American tribes, ie respecting the life of the animals you hunt and so forth, so I built basic religious principles around that to construct her world view. It made for some interesting conflict with devoutly religious Altana worshipers, though since Ash is at heart a diplomot nothing escalated lol.
Anyway if I were you I wouldn't go deep into it until you played the game and talked to a bunch of NPC and had official lore.
On 100% made-up stuff I think its tricky because you have to make sure it doesn't conflict with official stuff.
Definitely wait for the Lore to comes out. My approach is to also talk to all the NPC to get a feel for things. Example:
For instance I have a character that is an Elshimo Mithra from Khazam and I noticed that the priest there called them heathens and was there to convert which severl resident mithra didn't like. Then I looked other things up and saw that the mithra there were basically a tribal culture that worshiped nature spirits, aka the avataars, and gave offerings to Ifrit. All other indications reminded me of Native American tribes, ie respecting the life of the animals you hunt and so forth, so I built basic religious principles around that to construct her world view. It made for some interesting conflict with devoutly religious Altana worshipers, though since Ash is at heart a diplomot nothing escalated lol.
Anyway if I were you I wouldn't go deep into it until you played the game and talked to a bunch of NPC and had official lore.
On 100% made-up stuff I think its tricky because you have to make sure it doesn't conflict with official stuff.