Jason recently posted an update of his 9 Principles of Strategic Sorcery. I have personally verified in my own practice each of the 9 Principles he lists. Together they comprise the most salient points I would want to teach people about doing practical magic.
I strongly recommend that people interested in learning the fine art of practical magic take Jason's course. Of all the magicians I know, I trust him the most to take over the Supernatural Assistant Course because he's so well grounded in his approach, and I know he won't turn the Supernatural Assistant into some end-all goal of transcendence and Enlightenment. He's been there, done that, and has the wisdom to prove it.
But every once in a while, I get emails from people in his course who also are fans of my own work asking things like, "I'm in his course, and I was wondering... do you do all that meditation he recommends?" And of course, the answer is hell no. I don't practice his style of magic at all. He's a lot more pagan than I am, even though he's also well-versed in Christianity. He's been immersed in Eastern practices, and had experiences that formed his approach that I will never have. His experiences and my own, while leading to similar conclusions, have been very different. As a result, the framework, the context of our magic is very different.
The meditation thing is a good example. I am a strong advocate of Contemplation of the Divine. I think that the most beneficial times I've spent with the Spirits has been in a meditative state. The Visions of the Spheres, the actual time spent in communication with my HGA, the spirits of the Lemegeton's Goetia, and all the Archangels of the Planets have taken place in a state of no-mindedness that I only ever approached outside of ritual during my early attempts at meditation. I also believe that until you've learned to still your own mind and recognize where your own thoughts come from in your head, you will have a very difficult time differentiating between the Voices of the Spirits and your own meandering thoughts. The best way I know of to learn to do this is to practice meditation outside of ritual.
But I don't practice regular meditation. I reach these contemplative states as a result of the presence of the spirits, or by being in the presence of God. Within my context, the meditative state is a side effect of the magic. Just conjuring Gabriel using the Modern Angelic Grimoire techniques results in a changed state of mind. I gave a course on the text at a Thelemic Lodge a while ago, and at the end I conjured Haniel. I looked around the room and saw that everyone had been drawn into a deep contemplative state when the Archangel manifested in the crystal. Ok, maybe not everyone, maybe one or two weren't all the way there, but even the ones who weren't in a deep meditative state were in at least a light trance state.
Within the context of my magical studies and experiences, I've developed a different approach that accomplishes similar results. Yours will be different too, and they should be. Your magical system is going to be something that comes from a unique context that shapes how you do magic.
One of the things I like a lot about Jason's 9 Principles of Strategic Sorcery is that they are distilled to their pragmatic core. They are basically the same core principles Solomon wrote about in Ecclesiastes, that Blake wrote about in the Marriage of Heaven and Hell, that Agrippa teaches, and that I have reached in my own pursuits. How they manifest in your own Work is not going to be the same, but I'm confident you will find a core of truth in the 9 Principles that resonate throughout your experience.
But you should always have a shaker of salt with at least a grain or two ratttling around in the bottom when you approach any magical instruction. Salt flavors foods differently for different people. It makes the flavors blend with your taste buds. I sell the Modern Goetic Grimoire, and I hope that it helps people learn to have the kind of success with the spirits that I've had over the past several years. But it's not traditional, it's not "by the book" conjure magic straight out of the grimoires any more than my Modern Angelic Grimoire is. It may or may not be for you. I hope that when you read it, you find the things that fit into your own context and use the magic to change your life.
I'm not saying pick and choose. You'd damned well better have a framework, or context to put everything else into, and it better be based on something that reflects the system you're trying to use. A Chaos magician needs to stick with his or her own made up sigils to release the power of their mind, and had better not try to conjure HCOMA and Ashtoreth at the same time. It doesn't work that way at all. If you're going to use the grimoires, the Solomonic tradition, you'd better have a monotheistic or neo-platonic framework as your core belief structure that puts God above all the Spirits. If you see the spirits of the grimoires as self-evolved entities of specific cultures that rule over some aspects of the human subconscious, there's no authority structure you have to manage them. They'll end up running you, whether they're angels or demons.
Above all else, create harmony in your context. You will reach the understanding that's presented in the 9 Principles if you keep harmony as your goal.