In Iceland up until modern times, Galdrastafur, protective staves, were used by the rural folk as they were believed to ward the inscriber from negative events and to give good luck. The runes that form the Norse Futhark alphabet also have a similar purpose apart from their significance as a writing system. These kind of runic symbols can be found all across Europe, though Iceland provides the best preserved tradition with a more extensive list of staves.
Galdrastafur, depending on the intent, should either be drawn on one’s self, tattooed, put on one’s clothes, put on the clothes of the one that you intend to bless/curse, or on a particular item, this all depends on the intention of the incantation.
The Galdrastafur we have today have been passed down in what are known as grimoires, a kind of “spell book”, if you like; it is my suspicion that many have these books have been confiscated by the church of the centuries and comprise a large portion of the confidential Vatican archives, though I have no concrete evidence of this. The oldest known Icelandic grimoire dates from the 17th century, before which point it can be assumed the grimoires were passed down through word of mouth, which became more difficult as Christianity encroached.
One should be wary of the authentic of Galdrastafur, particularly those from a modern or relatively recent source. The Galdrastafur recording in the earlier annals are more likely to be authentically pagan and have pre-Christian roots.
Here is a extensive though by no means comprehensive list of Galdrastafur as well as how they should be used. I have acquired these grimoires from the archives of the National Museum of Iceland in Reykjavik:
Að unni: Meaning “to have another”
Ægishjálmur: “Helm of Awe”

Angurgapi: Barrel plugger
Róðrstafur: Rowing stave
Veiðistafur appears in three manuscripts. I show here the Skuggi version in his 1940 Galdraskræður magazine. It shows 5 faces within the circles. The other two versions don’t, however they add mid cross lines on each arm.
Stafur gegn galdri: Staff against magic

Draumstafir: “Dream staff”
An array of runes/staves: Miscellaneous purposes
Further resources on staves:
http://users.on.net/~starbase/galdrastafir/galdrastafir.htm