All magic users should pick a particular style of performing magic, with application to both in-combat casting and the more involved out-of-combat effects. They must always be something that can be interrupted or blocked by restraints, for game balance; it should also be well-detailed so you can visualize your character well.
For a Western Hermetic flavor, stick with the standard “wave your hands and say the magic words” (which may be anything from mnemonics to help you get into the spellcasting mindset to Words of Power, depending on the island) in combat. Draw complicated diagrams, burn incense, and go for the whole compliated Qaballah-looking style during rituals. Feel free to have glowing signs and sigils appear around you in the air in combat, or have a big glowing pentacle at your feet as you fly. This is the primary style on Élas for wizards and Children of the Dragon priests.
A style inspired by classical Taoism, the default Feng Shui setting, and shodo, the Japanese art of calligraphy. This does not involve words normally, but does require sketching ideographs on paper or in the air with appropriate materials. If you’ve been separated from your brushes and paints, you can still bite your finger and draw on your palm in blood, or use enchanted fingernail sheaths to sketch glowing sigils in the air. Out of combat, go for elaborate paper talismans and bizarre concotions of herbs. This is the primary style for Sheflek wizards.
A notion inspired by Barbara Hambly’s description of a witch who could summon fog by brushing her hair (probably in The Silent Tower or The Silicon Mage. Weather witches are a form of druid who specialize in weather before plans; they grow their hair out long and adopt a variety of styles. Straight, unbound hair can be brushed for rain and fog; thick braids control winds; and tight braids hurl lightning. (These are something to fiddle with in combat, rather than something that gets burned or cut off in the process.) If their hair is burned off or otherwise removed, they can make do at penalties with bundles of fiber torn from clothing or extracted from plants
This is the classic Buddhist style of chanting sutras while forming the hands into the stylized gestures called mudras; similar such gestures are seen among ninjas as kuji-kiri. The big Buddhist rosaries can come in handy as accouterments as well. This is the primary style for Pyramid priests.
A classic bardic notion seen in Alan Dean Foster’s Spellsinger series: a mage who works their magic through song. Some might operate entirely through instrumental music, while others might purely sing; there are a number of ways to interfere with them.
This should have its own archetype with Martial Arts, Sorcery, two fu powers, and two Sorcery schticks. This is the style from movies like Kung Fu Cult Master and Storm Riders: over-the-top martial arts that include massive special effects. The Mystic Martial Artist is required to keep their Martial Arts and Sorcery skills no more than two points of AV apart.
Somewhat inspired by Final Fantasy VIII, where the characters pose and flashy special effects happen around them. Hey, if it looks cinematic and has the necessary limitations, it’s balanced!
Other options include singing or chanting spells, smoking mystic herbs to achieve mystic insight... Druids tend to perform divination by observing patterns in leaves and the flights of birds and casting spells with bundles of herbs and incantations, while weather-witches, functionally the same, call rain and fog by brushing out their long hair, wind with loose braids, and lightning with small, tight braids.