Building on the legacy

On November 4, 2012, Ellie Mayerhofer wrote on my website, I was wondering if you had any advice for a story I'm writing. It's a twist on Red Riding Hood, but I'm including at least two other fairy tales in it. I have read several versions of RRH, and seen a few too. I'm trying to write something completely original, but sometimes I feel like the story is too much like other versions of RRH. Is there any way I can be sure that it is completely original and not too much like other versions? It...