Magical techniques are the supernatural means that one uses in order to perform magic, i.e. to influence events, attain objectives, or acquire knowledge. etc.
Over the ages numerous techniques have been tried all over the world by different civilizations. Strictly speaking, even meditation, creative visualization, prayers and affirmations all could be considered magical techniques, as well.
Typically, however, when speaking about magical techniques, people think of spells, invocations, curses, chants, rituals, etc.
See also '[magical tools]' for the objects that are used in these techniques.