Does anyone know a good place to post a ff about Snape with an OC? I haven't written it yet but if I could find a place to post one, I could finally get a start on my idea! lol

あなた may use FanFiction.net. It's easy to use.

Wherever あなた post, please put a link here so that we may go and read it, okay ?

(A small piece of アドバイス from one fanfic writer to another : start your story, no matter what. Don't post it right after starting, because if あなた need to change the plot, it's もっと見る difficult to change. Once あなた have completed about 80% of your story, then あなた can post. So あなた have time to look for a place to post, don't worry !)

sycophanthex.com has a Snape/OC category in their Occlumency archive, where I'm currently posting mine. I think it's a great site and hosts lots of different Snape fanfic.

I post mine on fanfiction.net, Occlumency and The Petulant Poetess

Fanfiction.net is a good place for all sorts of fanfics. good luck!