I never done this meditation to see what I was in my previous lives. Can you share a bit of your experience? How do you know that what you seen wasn't the result of your imagination? Can a past life regression be done in a lucid dream (since in that case both our consciouss and unconsciouss minds are active)?

Its probably better if you just do it with no expectations that you might have after hearing other peoples 'experiences'.

If you go based upon someone elses experiences that might not be good as it may not be the same for you so dont expect stuff let it happen

You probably want to be alone as sometimes people pick up on others thoughts in meditative states if you do this though and not lay down especially if your tired or you may enter a lucid dream (that probably isnt accurate) and wake up later or just fall asleep. That is what happened the one time I tried my own version of this. I didnt know the JOS had a page on this ill have to look it up.