You may not have written instructions on what to do in a ritual, as the Egyptians do, but I doubt that there was any general pattern anyway. The thing about Heathens is that you have enough literature - myths and sagas - to know how they felt and thought, and reconstructing the attitude seems to do it. I always say I can understand where Heathens are coming from, and likewise traditional ethnic pagans outside the West, in a way that I can't always relate to Wiccans and the pick-and-mix types.
Oh, yeah, we can definitely reconstruct the attitude. ...well, of a specific group from a period of about 2, 300 years, give or take, the later half of which involves literature written by Christians. Also consider that in a Swedish Viking's grave, they found a Buddha statuette. Don't try telling me said Viking wasn't at least somewhat influenced by Buddhist thinking during that time in India, or that other Swedish Vikings trading with Muslim countries didn't get at least somewhat influenced by Muslim thought. Not saying they became Buddhist or Muslim outright; just saying "pick-and-mix" is probably itself a pre-Christian tradition of sorts. Heck, to me, it seems an inevitable result of polytheism combined with cultural exchange.
I'm an Anglo-Saxon-esque Heathen, and we know almost nothing about what the Anglo-Saxons as a cultural whole might have been like, assuming there was any kind of cultural homogeneity among the, at least, three (four if the Frisians were in there) quite distinct Ingwine tribes involved, before Christianization; let alone the Norman invasion which almost wiped out whatever might have been left.
Besides, pure reconstructionism in this context isn't really possible. With Hellenism, Religio Romana, and Kemeticism, it's also easier because those cultures were very similar to our own, in that they were incredibly urbanized. A good microcosm for how similar Western Civilization's panculture is to theirs, at least in their urban centers, is that the pre-Christian Romans had what I can only describe as "Classical Fast Food", including a dish we now call the hamburger. It's easier to apply these pre-Christian/Muslim Mediterranean urban religions to modern urban life, than it is to apply pre-Christian traditions of Northern Europe. Don't forget, the vast majority of people practicing those traditions, living in Northern Europe after West Rome's collapse, were farmers.
I'm not a Northern European farmer hardened by Sunless Winters and Clouded Summers. I'm a sheltered suburban kid from Summerland (that is, California) raised by Sonic the Hedgehog, Doom, and Pokémon. I've never eaten animals that I once fed with my own hands, nor had to face the hardships resulting from a bad harvest. I tried my hand at sustainable farming on a 3-month live-in internship a few years ago. Left after 5 weeks from sheer exhaustion that left me barely able to walk or even speak (don't get me wrong; it was an AMAZING experience, and I kinda want to try again someday
).
However, many of those pre-Christian traditions actually did survive in secularized (and sometimes Christianized) forms. I'm convinced that the May Queen and King celebrations in England are the modern forms of pre-Christian worship of Freya and Frey, and that they even exist in modern American culture in the form of the High School tradition of the Prom Queen and King. Heck, even Santa Clause/Father Christmas is thought to be a continuation of old traditions of worshiping the Yuleking; that is, Woden. In these cases, it's more a matter of reapplying their polytheist contexts, at least for ourselves as Heathens. I also have no problem with "Heathenizing" some technically post-Christian traditions from Northern Europe that have decidedly pagan-esque imagery. I've already written (not yet posted) a fairy tale about Frey wooing the Goddess Eostre (whom I straight up name Easter in the story) when the latter makes the former go on, well, an Easter Egg hunt. As an Anglo-Saxon-esque Heathen, I also apply other traditions of England, and the British Isles as a whole, such as deifying Robin Hood. I've considered joining OBOD at some point, as well. If I'm ever in Ireland, you can bet that I'm gonna give some kind of offering to the River Goddess Shannon.
Just like, when I was in Japan, I gave offerings to, and prayed at, some of the shrines. I wasn't Heathen then, nor was I ever a follower of Shinto (and most likely never will be because I'm not Japanese at all), but when I go back someday, I'll do so again when allowed. I don't have to actively follow a region's specific polytheist religion in order to pray/give offerings to the Gods and wights who live there, as long as I'm allowed to do so. One of these days, I'm going to visit Greece, hopefully with my dad. From him, I have a lot of Greek blood. I will absolutely take part in whatever rituals to the Gods I'm allowed to. (EDIT: For clarification, no, I don't practice any Native American rituals or honor any of the local wights, tempting as it can be sometimes, since I don't know anything about them or how the local Tribes worshiped them if at all. Cultural appropriation is bad. Hence why I always stated "as long as I'm allowed" for the above things.)
Hethen Revivalism is all about bringing back the spirit and meaning of our pre-Christian traditions, but applying them to modern life, as opposed to trying to recreate all parts of pre-Christian Northern European life and culture. Frankly, some of the things they seemed to value are best left in the past. You'll notice that I title myself as a Proud Ergi.