So My great great grandmother was Native American, & of course for YEARS I thought it was Blackfoot

[Gormy Cuss]

2. Do you have the photo?

I'd start there and try to get an ID on the headdress. That should narrow down the tribal groups at a minimum.
Also, if you know her surname and where she was born, try to match that data to names of tribal members in that geography.

It also is important to try to trace her through census records, paying particular attention to where her parents were born because if one or both were from other areas you may need to look in those areas for the tribal link.

I had an Indian grandfather who had been adopted into a white family as a child and we didn't know much about his biological family. He died as a young man and rarely talked about his bio roots other than to describe himself as an Indian. We used to think he was from one tribal group but through my research it 's far more likely that he was from another, the group living where his mother was born and where his father had lived and where many tribal members had his father's surname. My grandfather and his siblings all looked very much like members of that tribe and not at all like the other tribal group.