I had done features that has aspects of storytelling to it, but the idea of crafting my own story, scared me to death. What if it was horrible? What if I wasn't nearly as good as I hoped to be? I don't think there is anything more paralyzing that fear of failure. It can cause you to make excuses and put things off for weeks, months or ever years.
I ended up taking the plunge and submitting a story for a writing contest. It was the first story I ever wrote, and it won. About three months later, it was optioned for an independent feature film and my foray into world in entertainment began. The feeling of having something published and having people read and love it is amazing.
Anyone that wants to write horror should. It won't be easy, and it's going to take a few tries to perfect it. I know my story went through about three different drafts and that was only a short story. Imagine a 50,000 word book. Life is too short to worry about regret. It doesn't matter if your 18 or 50. If you have the urge, then give it voice.