theres basically no wrong way to do it, what worked for me personally for my goals was using the Corpse Pose from yoga on a hardwood floor. it can take a few minutes to 'finalize' your position, make sure you are truly comfortable enough to remain motionless. then i would focus on simply perceiving my surroundings, all of the sensory input coming into my mind, constructing a kind of mental map of the surrounding world. i've done it with eyes open and closed, with eyes open i get a kind of pulsating television static overlay on my vision and a weird mental state good for existential pondering, with eyes closed i can let my eyes do what they want as they for some reason tend to kind of 'roll back into my head' (point upwards to the edge of my eye socket and kind of twitch), which for me can produce either generic pulsating blob phsophene-like visuals, or in rare cases detailed pseudo-hallucinatory experiences (visuals in the 'minds eye', not in actual sight)