As previously mentioned, knowledge is power. Research and study.
That said, I practice hedge-crossing, an shamanic approach of soul travel based on indigenous practices in European Cunningfolk and Witches.
I have a few posts on my blog that I'd like to share a bit of here for you.
> How to start hedge-riding?
To pass through the veil, to the worlds of spirits, one must have madness, cunning, imagination, and energy.
Firstly, one should master protection and wardings, for the beings on the other side are far above human morality, thinking with the logic of the mad, capable of inflicting much ruin upon a foolish mortal that offends them or falls for trickery.
Become well versed in the riddles and the rules for interacting with such beings. Research myths, folklore, and fairy tales. All offer advice that is valuable to any witch whom is or will wander the realms beyond our own.
Do not eat what they may offer, especially without trust. Be careful of inviting them home. And don?t forget your own words of power, especially those to invoke memory of returning home. One simple phrase is ?Rentum Tormentum, in the Devils Name? to return you instantly to your body. Ingrain this or any other safe phrase into your head.
Come up with a name there. True names are a means of power over something, and your true name may be your nickname, it may be your full name, it may be some hidden name revealed in gnosis, all depending on your paradigm. Become your alias there. Let it resonate with your spirit.
Then it is experimenting with medium, means and conditions to induce trance, a stimulus. This stimulus will be a repetitive action or posture done in a ritualized method. It could be setting, drumming, entheogens, silence, dance, posture, lucid dreaming, mantras, anything to spark your heart into strumming madly or lulling the mind to a simple slowness, in any combination that you find as the correct method for you. Use your senses to your advantage. Use the scent of a candle or incense to bring your mind into the state you want. Use the candle light, sigils, darkness as your allies. Use the solid earth beneath your feet to make you still as a tree. Visualize a fire under your feet to dance with madness. Hear the mp3 of a drum, or the shaking of the rattle in your hand. Taste the mushroom and associate its qualities with where you are going.
That?s the thing about hedge-crossing, is that no two whom do it will have the exact same stimulus or learning. Experiment, learn, and proceed on your terms. It may take a day, it may take a year, but keep at it, and it will come to you. And it will get even easier as you make it more weekly and daily, as you flex the muscles of your mind.
Fly free, and wander your crooked path with curiosity and caution.