That guide actually isn't too bad, I was expecting it to be shit, lol. I find that for a lot of people the fear of having a bad trip is what brings it on. Especially people who are new to psychedelics.
fear causes hesitation, and hesitation will make your worst fears come true. so just don't be afraid of having a bad trip, and make sure that your enviroment is sound enough so that you don't have any enviromental stressors. and make sure that your current state of mind is capable of handling what is about to happen; don't do it in a time in your life that you have a ton of stressors.