The Vikings were the last great pagan European culture prior to their conversion to Christianity in approximately 1000 AD. What we know about their religion comes primarily from the Prose and Poetic Eddas which Snorri Snorrson wrote sometime in the early 12th century . So the exact role of sorcery and witches is not known.
The Vikings believed in seidr or the practice of witchcraft. (quite probably like shamanism). There was white and dark seidr. White seidr included the arts of healing , controlling the weather and the ability to call up game and fish for the hunter. The black form included the power to raise the dead, curse an enemy, blight land and destroy love.
There is some evidence that the ritual connected with seidr included chanting as there is an Christian era law which prohibits the use of spell-chanting or galdresang. It is also possible that seidr had some relation to spinning and the distaff as spells were often supposed to spun or woven.
From various Eddic poems, particularly ‘Loki’s Quarrel’ stanza 24 it is clear that most practitioners of the art of seid were women as Loki taunts Odin as being less than a man for having practiced it. It apparently included tinkling of bells and womanish body movements.
Some people speculate that the Oseburg ship does not contain a queen but rather a great sorceress. The reasoning being that among the grave goods was an ornate staff which is associated with witchcraft and several cannabis seeds.
Unfortunately most of the rituals have been lost once Scandinavia became Christian Like many other places, witches went from being held in high esteem to being persecuted. This reached a height during the 17th century when in northern Norway over 150 people (mostly women) were killed as a result of witch trials. In 2011 Queen Sonja of Norway opened a memorial to the victims.