Kenaz has two really good posts that I just got to today about "demonic obsession." Very interesting and useful information for those pursuing a conjure-magic path.
Initiation comes with many pains and trials and ordeals in the mundane world, but it also comes with a great deal of benefits. If you want something like the protection Kenaz mentions in his post, but you're not into Vodou, or if you're like me and the idea of "organized" spiritual/religious organizations gives you the heeby jeebies, there are several options available to you in the comfort of your own home. Comes in handy for those stuck far from any occult Orders too.
The Abramelin Rite has been compared to the receiving of your "head" in Palo by Aaron Leitch, if I remember right. Gaining Knowledge and Conversation with the Holy Guardian Angel leaves you changed in a way that keeps you from being readily demonized by any spirits, whether they be the remnants of a deceased human, or a never-incarnated spirit entity you've conjured to do your bidding. That's why I strongly recommend getting at least your Supernatural Assistant before beginning any type of Work with any spirits classified as "demons". He covers your ass for you in ways you rarely appreciate.
Of course, my house caught on fire anyway, so don't think it's a "get out of all major catastrophes free" card. Life, apparently, doesn't work that way.
Gaining initiation into each of the Planetary Realms is another method of obtaining a degree of protection from the spirits. Those who have mastered the Trithemian method of conjuring the Archangels of the planets (or who have my Modern Angelic Grimoire) can gain initiation into these spheres through the Archangels of the Planets.
If you're looking for protection from the lower Spirits, I'd assume the Sphere of the Sun would be the best bet. The Supernatural Assistant is a Solar Spirit, and Crowley puts the HGA in Tiphareth, rightly so, imo. Michael, the Trithemian Archangel of the Sun, is also the Archangel who "kicked Lucifer's butt out of heaven" as Kenaz says, and initiation into his sphere will raise the tincture of your own sphere to a vibrational level that is incompatible with the spirits that most often bring people harm. The Supernatural Assistant course I was offering until recently was an immersion into the Sphere of the Sun as well as the obtaining of that particular familiar spirit.
Be warned, the crucifixion of Christ is the classic metaphor of the initiatory experience of the Sun. While I do believe that Bune was responsible for the fire in my house, I was ALSO doing the course work I prescribed for my students, and had taken on the mantle of Hierophant for the group. I had linked myself to their initiatory experiences, and this fire has been very much like a Solar Rebirth. I wonder at times if the fire wasn't the result of the Course Work I was doing, amplified by the spiritual link to several other people going through it at the same time. And then Bune just took advantage of the fire to provide me with nearly the exact dollar amounts I requested...
Feh, that's the trouble with this magic thing, there are so many things you can assign a causal relationship to your physical experiences. I'll never really know if Bune or the Supernatural Assistant Course was the root cause of the fire, or if it was just "shit happens." At least, not as long as I'm in the flesh.
But yeah, initiation is always a death-and-rebirth experience, in some ways, and the spirits that obsess and possess lose a fingerhold on your sphere after you've passed between the realms and returned to this one. It's a good thing to have.