I believe the best way is just to quit cleaning your hair, right? And you just let it dread up on it’s own. I have a friend of a friend story about the “natural” dread process. A friend told me that he had a friend growing up who just quit washing his hair and it dreaded up. He had them for a long while and finally decided to cut them off. He had one in the middle that was a little bigger than the rest so the barber cut it first and when he did, the dread was hollow and a bunch of baby spiders came crawling out. I was told he shaved his head after that.
I had a friend who dreaded her hair at one time and she bought a product that made the hair dread up but she could occasionally wash it so that it was at least a little less gross. I can’t remember what it was called though. I can ask her and try to get back to you.