I never thought I wind be a writer. I had an idea for a superhero for several years based on my own life experiences, a very powerful superwoman working a low-paying retail job in her secret identity. One day I sat down and stated writing, thinking that I would just put down a few ideas. But then I just kept going. Next thing I knew, I was sixty pages into this thing. It was almost as if this story was forcing me to write it.
I read them all. It's tough to deal with the bad ones, but it's part of the deal when you put yourself out there. I think it takes time to separate the ones that have good constructive criticism from those that are just reflexively negative.
Above all, do this with a straight face. No matter how "out there" your idea might seem, you have to commit to it a thousand percent. If you don't believe in it, nobody else will.