There are many, and one may use a combination of two or more methods, as well, so it can become very personal. Dance, spinning, drumming, chanting, or something else rhythmic are very, very common over the world. Sensory deprivation is another frequently used - often various types of masks that can limit vision. Breath work is often used, such as is also found in some forms of meditation. Meditation itself can lead to trance states. IMO, walking meditations are particularly useful for trance, linking back to dance in perhaps a more controlled way. Heck, even something like flogging has its traditional uses to achieve trance states - Gardnerian Wicca doesn't include a scourge for nothing! Various aspects of asceticism can also be used, instead of the more 'ecstatic' methods like dance tends to be. It is best to research and try out several different methods.
I sing of you, blessed, night-winged Dream, Messenger of things to come, greatest prophet to mortals, in the quiet of sweet sleep you come silently and speak to the soul.