I like to have my room perfectly in order, everything in their respective places, and by perfection i mean insofar as my own perception of the word, as I know perfection already exists and is innate to nearly everything, imo, so there is in turn, no perfection to achieve. The room being clean and in order in turn transposes consciousness in a clean and orderly way, ime.
Having eaten a light, fresh, locally grown meal a few hours prior, a couple glasses of water. You are what you eat, no? A series of simple asana/kriyas about an hour before smoking, allowing the vital organs, tissues to function in a relaxed, smooth, natural manner without much in the way of physical discomfort. A warm shower to relax the body getting the blood to flow near the skin, and the last 2 minutes being in relatively cold temperatures, causing vasoconstriction, pulling fresh blood from the vital areas of the body up through the capillaries to warm the body, eventually back through to the vital organs, essentially a flush of sorts, allowing great circulation. After getting out, the effects of the yoga followed by this shower put me in an incredible state of mental clarity and serenity.
I set up high energy music typically, as I find the DMT experience will take what you give it and weave message laden images through it's infinite tapestry, spinning magic before your eyes. Also, ime, music that strikes chords deep within, invoking strong heart-felt emotions will mesh into the experience as well, facilitating healing, unity, euphoria, peace, very beautiful, deeply personal, entheogenic experiences.
Lastly, I make a comfortable space that transposes a sort of supreme comfortability within myself. Dim lighting with several candles, and either an upright supportive posture or laying down comfortably. Either way I attempt to make my posture as symmetrical as possible - unity/stability of form.
This is the backbone of my ritual every time I smoke. Trust me when I say - this experience can profoundly propel you deep within things you never imagined and to depths of your Self that can only be known as divine. This experience takes what you give it, nothing more nothing less.
Some people might look at this as excessive, but trust me when I tell you -it's not, and invite you to do the same.