Having just finished reading Icons of Power: Ritual Practices in Late Antiquity, I think I'm in a good place to talk about real magical and ritual practices of Antiquity and how they can inform the design of fantastical systems of magic. The first and most important thing is, of course, to ditch the term magic, which was a polemic used to compare people with the hated Magians of Persia who were presumed to perform profane and unholy arts, particularly because they were said to sacrifice human beings to their gods (as first reported by the Father of History and Father of Lies, Herodotus).
Thankfully, there is actually some real antique evidence that rehabilitates or reinforces (or at least informs) the use of spoken-word spells and gestures, so I don't have to feel so damn bad about all that wizardly hocus pocus in my games (do I have to feel bad if it doesn't have historical precedent? Probably not).
The old divisions of magic/religion as elaborated by Frazier in the Golden Bough (magic demands things of supernatural beings, religion is a supplication) have been swept away by new theoretical frameworks. "Magic" itself is a negative term used to denigrate the religion of the Other and prove that it is somehow inferior to one's own. This can include branches of non-orthodox or orthoprax religions that the polemicist actually shares beliefs with.
The Types of Magic:
This is the most similar to the magic of D&D and the Lord of the Rings. Janowitz discusses the use of language as a non-semantic, pragmatic tool—ie, language that carries no meaning as language but rather causes actual, automatic effects in the world. The most common instantiation of this magical speech in the Late Antique period is actually in the names of Gods and daimons (the kind of spirit that may be either good or bad, as according to Greco-Roman mythology, not the "demons" of Christianity, though those too fall under this heading as creatures compelled by or named by magical speech). Necromancers and magicians bind and control spirits for what Janowitz calls "automatic effects" that is, spells or formulae that are effective no matter what the original intention or semantic setting is. This is similar to the accidental out-loud reading of a magical tome causing the spell to become active; the effect happens because of the language.
The development of non-semantic expression and automatic effects is somewhat similar to the way that magic works in the 10th Age, so I'm pretty pleased with this. While the efficacy in D&D doesn't necessarily rely on messenger spirits (unlike the root of D&D magic, Jack Vance's Dying Earth) it still incorporates a number of important ideas from the antique world.
Here's the meat of this blog post, the thing which you will probably find most useful—Janowitz's tables of rituals as described in the Book of Secrets, a Jewish text of (presumably, though like all Late Antique magical texts only versions from the 13th-15th centuries are extant) Late Antique origin. All these rituals are great.
Ritual Purpose: Healing
Ritual Practice: Burn incense, chant
Ritual Purpose: Destroy an enemy (creditor, etc.)
Ritual Practice: Fill vessels with water, smash vessels, tell spirit this is what you want it to do to your enemy
Ritual Purpose: Know future
Ritual Practice: Put written slips in oil, imprecation of the Sun
Ritual Purpose: Influence king
Ritual Practice: Write names of angels/spirits on the heart of a lion, adjuration to Aphrodite
Ritual Purpose: Enter presence of a king
Ritual Practice: Anoint self with mixture made from previous heart
Ritual Purpose: Bind yourself to a great woman
Ritual Practice: Collect your sweat in a flask, bury it under her doorstep, adjure spirits
Ritual Purpose: Speak to ghosts
Ritual Practice: Face tomb, hold oil and honey, adjuration of Hermes, singsong release chant
Ritual Purpose: Give enemy trouble sleeping
Ritual Practice: Bury dogshead with spells written on it nearby
Ritual Purpose: Light an oven in the cold
Ritual Practice: Write angel names on a sulfur lamp, place in oven
These are some of the most interesting rituals present in Janowitz's chapter on the Book of Secrets. She goes into detail about some of them, though it is extremely theoretical. It's a good book, though absolutely not necessary to play and enjoy any kind of game or even to enjoy fantasy. You know me, though: always looking for the next bit of real information to incorporate, study, or devour.