One thing to keep in mind, that is often overlooked, is that with the ethnic tribal divisions in North America there were religious divisions as well. some like the Plains and Eastern tribes worshipped the Great Spirit and then sought to appease nature spirits. Others like the Pueblos had the concept of the Thunderbird and then the MesoAmerican tribes were polytheist with mutliple Gods and spirits to worship. These did not always coexist peacefully--religious war seems to be in the makeup of mankind.
Also, it has been pointed out that the Native American religions we are familiar today are not identical to what the earliest American dwellers believed and this is important. Around the time of the huge die offs from disease many tribes experienced a prophetic encounter that changed their belief systems considerably--for example the prophet among the Algonquin tribes. Other such experiences occured among tribes after being forced off their tribal lands by other tribes. For example there is the Cheyenne experience with the teachings of Sweet Medicine (Who brought the Medicine Arrows and taught them to hunt Buffalo) and Erect Horns (who gave them the Medicine Hat and the Sundance), and among the Lakota there was the prophecy of the Medicine Woman who would return as the White Buffalo. These are all post contact developments and you can see the world they were trying to respond to. Later you see such things as the Shadow dance and Ghost shirts and other practices that sought to roll back to earlier times, and undo the conquests of whites. Now there is an effort to create a conglomerate religion among NA tribes known as the Native American Church--using Southwestern Peyote and the Plains Sweat Lodge--but mixing so much that most traditionalists among the tribes reject it.
Even among tribes of similar practice the beliefs and details could be quite different. For example the Arapaho, Lakota, Crow and Shoshone all practice versions of the Sundance. To simply see the arbors built one would assume the practices and beliefs were the same, but the reason for the dance and the way they were to be done were different among each. The Crow and Shoshone were nearly identical, but the Cheyenne and Arapaho, as enemies of the Crow and Shoshone, had different practices and held theirs together--every Cheyenne sundance has some Arapahoes represented, with a special section set aside for them. The Lakota is the most unique of them all, when you see a sundance in the movies it is usually Lakota based. Among the Cheyenne the sundance was more sexual-fertility based without the self mutilations and self torture often seen in these scenes.
---------- Post added 03-25-2010 at 04:25 PM ----------
Just for my own need to have handles to attach here and there, you call yourself a pagan (spaking now to Pagan) so I assume you seek to emulate Briton beliefs prior to Roman and Christian influence (Your words). I wonder, are you seeking to emulate the beliefs and practices of the druids or of the pre-Celtic peoples of the Isles?
I ask this because I have known many people who called themselves pagan but the name gives so little information because it can mean so many different beliefs and gives so little information. When one says they are Christian, Buddhist, Taoist or Islamic we have an idea of some basic beliefs they hold to but pagan can mean so many different things.