When it comes to astral projection or similar practices, experimentation is going to be your first key.
Finding your means of doing so is experimenting with a medium, means and conditions to induce trance, a stimulus. This stimulus will be a repetitive action or posture done in a possibly 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.
Finally, realize that it may take you a year even or longer to accomplish this. It doesn't come easy for everyone for reasons. Because it's like doing a new activity and building muscle. Baby steps, and flexing the mental muscles. Some people might have a better affinity for it, but it has to be learned regardless.