Paperwork on Native Americans is often scarce and lineage is difficult to prove. It can be a lifetime of searching documents, microfilms, books and libraries. I recommend your first step be determining whether or not your ancestor(s) were Native American to begin with.
Legend and storytelling have been around forever. Rather than spinning your wheels on a wild goose chase, prove scientifically that your specific ancestor was of Native American descent. If you do definitively prove your ancestor was of N.A. heritage, I can refer you to one of several Native American research specialists.
Please review the other DNA services and contact me for more information.