Any magician, sorcerer, or witch that has an interest in astral projection should typically master one thing first.
That thing is meditation.
Mastering meditation is a must have for anyone who plans to astral project or it's shamanic equivalents. This is always extremely difficult in it's first few steps, but being able to quite your mind anywhere and visualize are extremely important, allowing you to shut down all auxiliary thought to focus your spiritual and brains processing power to a singular point or action, in this case astral projection. Doing so is entering trance, and trance is the goal. Not all methods of trance require meditation, but it's a well documented and used method.
I'd start by meditating for at least ten minutes a day, and working yourself up to twenty, thirty, and onwards. A good way to keep your focus on one thing is by staring at a candle in the dark as you stay still and ignore all outside events.