For me recurrent sleep paralysis turned out to be associated with sleep apnea. Both were reduced but not eliminated by adjusting sleep position (side rather than back as others have already mentioned), wearing a mandibular adjustment device (holds the jaw in a slightly different position to avoid airway obstruction). Similarly, some changes in consumption habits reduced occurrence: reducing alcohol intake and large/rich meals shortly before sleeping.

in my case these symptoms were the result of some abnormalities in my throat cartilage which eventually required surgery, but the above behaviour changes reduced occurrence substantially (approx 5 instances per week of sleep paralysis or choking to 1.2 based on 3-month diary). I made all the above adjustments together so cannot give any further indications about which of them might have helped. Or indeed, fully ruled out a placebo effect!

I didn't recognise the association between sleep paralysis and apnea but it was one of the first things the head & neck specialist asked.