Activation of the power of the grimoires to their fullest comes from two things. First you need to understand the context of the grimoires by studying a wide variety of approaches that were contemporary to one another. You need to read the Keys of Solomon, all the parts of the Lemegeton, the 6th and 7th Books of Moses, Liber Juratus, the Grimorium Verum, and most importantly perhaps, the Heptameron. You need to know the world view they are representative of by learning about neo-platonism, cosmic hierarchies, and Hermeticism. You need to know the politics of the time, and the doctrines of the Churches that were being tossed about.
Learning all that stuff doesn't take that long, really. I read like a fish breathes water. A couple of months on Joe Peterson's Esoteric Archive is enough to get your feet wet.
There's still another piece to activating the full power of the grimoires, in my opinion and experience, though that must be taken. Think of it as an initiation. You've got to be baptized in the Holy Spirit.
On a list I belong to comprised primarily of pagans who also happen to perform ceremonial magic(k), a recent post was about the Right Path. I explained in my best possible non-judgmental, non-proselytizing way that there are lots of different individual paths, but they all end up at the same place, eventually. I also included that you know you're on the right path when you get a vision of the universe and your personal place in it.
That's exactly what you need to really activate the grimoires. Knowing about the hierarchies is great, but until you not only know where your place in them is, but also know that you are in that place because you've been spiritually transformed, you don't get to really get the full benefits.
My transformation came from church. I got a spiritual baptism that changed me at the core. I accepted what Christ did on the cross on my behalf. I saw that he made right what had been wrong for so long. I felt the cleansing of my sphere. It was a truly powerful experience that literally changed my life.
THEN I made contact with my Holy Guardian Angel. The spiritual transformation was given an applicable framework. Specific tasks were given, training programs were enacted, and at each stage progressively my sphere was sanctified, purified, and reconciled more to the place where I could operate from in power.
It was like being trained to use the equipment in an Air Traffic Control Tower. I learned to read the weather (astrological conditions), the radar (astral viewing/scrying), the codes to give the airplanes (seals, sigils, names), and the most efficient ways to direct landings and take-offs so that the operations were strategically coordinated (the frameworks of the grimoires). I learned disaster recovery techniques (sell the crystal skull and set wards against Tezcatlipoca), and emergency situation protocols (how to use the lead Seal of Solomon from the Goetia). I learned the ins and outs of the job, and then I got to work at the controls myself with the trainer right behind and slightly above me making sure everything went smoothly. We started at a small airport with a few airplanes (the Art of Drawing Spirits into Crystals attributed to Trithemius), and worked my way up to more advanced Work involving a lot more craft (Enochian now, sheesh).
Every step of the way, the transformation I experienced in church during a praise and worship service has been added to, magnified, and made more meaningful. I no longer attend church regularly. I relate to God through my magic, my meditation, my contemplation, and even in the back-aching inscription of alternate alphabets into wood, stone, and metals. I pray a lot more and talk a lot less. All the knowledge and conversation with my HGA, all the learning from books, all the conjuring of Angels and Demons, it's meaningless without that initial transformation.
Do you have to be a Hermetic Christian with Gnostic tendencies to get the most out of the Grimoires? I can't say you must, because I never got jack shit out of them before I was one. I don't have anything to compare it to. But I can tell you that based on my experiences, it certainly does help.