I have heard good things in regards to LSD helping headaches, regardless of their origin. Hopefully it will work well for you.
As far as preparing for the experience, I would say just make sure your tripping space is nicely cleaned and not too cluttered. I have found this to be a bother when tripping on any type of substance. Make sure to have a calm mind too, do some meditation for a while before taking it. Maybe do so for the week leading up to the experience, the clearer your mind the better it will be.
Id suggest having some good music playing too, anything that is mellow yet somewhat spacey and trippy is great to listen to for me. Or even something more on the rock side but not anything heavy, something like the Doors or the Beatles, these have been good choices in the past for me.
Have something around that will help you in a hard time as well. If things get to hectic, its nice to have something from the material world to hold onto and look at to remind you of where you are and who you are, something to ground you. I have even found myself holding onto my two foot acrylic while tripping to hard on mushrooms, thinking that if I let go I would float away and never come back. It helped me relax and realize that I was still here and not going to drift off into some strange place that I couldnt come back from.
Other then that just relax and enjoy the ride
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LSD can be a magnificent thing.
Everything published by Gone-and-Back are the mad rantings and ravings of a mind who yearns to be free and thinks he knows what he is talking about. However, these are just delusions made to feel that freedom, because that freedom will never come. Any experiments done are purely figments of the imagination, and are falsified to the highest degree. Nothing should be taken seriously from a crazy mans mind.