I'm thinking of writing a story on the site...

How should I start it? I don't want a plot, because I have one. I'm just looking for an attention-grabbing first paragraph.

I would like more advice on writing as well.

A good premise is that a character has a problem in their day to day life. Then something comes up, posing another problem (the main story problem). By solving the main story problem, they'll have to overcome the problem they already have. So start by showing this problem they already have. This is often a personality flaw. I don't know anything about your story so I can't give a specific suggestion, but just show a scene from their ordinary life in which this personality flaw wreaks its havoc.

That's sort of vague, but it's great that you're thinking about writing. For more writing advice, click the Resources and go to the knowlege base:
writing_tips.html
We have a ton of really helpful user articles about grammar, plot lines, and probably what you would like to see- starting a novel and how to write a great opening paragraph.
Good luck!

Antigone

Antigone- That would be this article on beginnings

However, sometimes it's best to stop worrying about exactly the best place to start a story and to just start a story. The beginnings of early drafts of a story are designed to get you informed about the story and figure out what you what to happen. As the author of that article, I can say that you can try to come up with a fantastic hook all you want but you'll probably have to rewrite the beginning once you have all the information out into the open. I've put all the information on the page in the beginning, then in the next draft I work all the information into more interesting action. I was still working on doing that— in draft 14 of the beginning.

So, yeah, worry more about just starting than finding the perfect place to start. You're going to be rewriting anyway. Just get the story out on paper and you can make it pretty later.

Like Rosey said, just start the story! The best ideas come when you start writing! Start in a place that grabs your interest. If your story needs a better hook, that's an issue for editing.

As others have said, just start. It's doing you no good at all to sit there just waiting for the perfect beginning to pop up on your Word Document, so just start typing. I know that sounds hard and maybe even ridiculous to you, but remember you can always change it later if you believe it doesn't fit.

Also, another tip of mine would be to open a few of your favorite author's books and see how they start. No, don't copy their particular opening strategy, but rather take influence from it. Do they start off with a fact? Or maybe they get straight to the point, and emerge their writing through the end of the story, as my favorite author Chuck Palahniuk tends to do, and just tell the story through flashbacks? Develop your own way of doing it. I like starting off with a hint as to what is going to happen as the plot develops ((lampshading, I believe its called?)), but that's just me.

Jump in, and wee!

Edit once finished. Just write, and finish. Those are your prime goals right now.