If we're gonna take this thread seriously for a moment;

I've been in the GM's seat give or take 4 times now, to varying degrees of success. I've always gotten past the interest check phase but beyond that I've had quite... varied results.

I've found that in order to have a good interest check, you need to have at least some elements (but not all) of the following (and I definitely have left some gaps but oh well):

[list][*]Being able to clearly articulate your idea. You may have the best ideas in the world, but if you can't properly explain what it's about then you're not going to get anywhere.
[*]Doing something that people are both asking for, and others aren't providing. This one's a bit more abstract, but what it comes down to is this: Interest for a generic fantasy adventure is always high, but if your adventure is too generic, and there's 3 other RPs already on the market dealing with the same thing, people are going to be playing in those instead.
[*]Knowing what you want. This isn't the same as having a detailed idea, mind. I've gotten away with posting an interest check titled "let's brainstorm a yugioh roleplay together" and I sure did draw a crowd from it (even if, when it got time to actual writing, it all fell apart). Thing is, even in that brainstorm thread I still laid out a few fundamental things I was looking for. Close to the anime, none o' dat meta shit, a lot of freedom in how duels unfolded (so no simulators). The details of the actual plot was for everyone interested to figure out together. This, too, was made clear. Set your boundaries and stick to them.
[*]Putting effort into presentation. I'm not saying "use colours, tables, images and gifs like your life depends on it" since, really, I don't do that either. But do try to format your text in a clearly readable, easily accessible manner. Organizing your thread to have a clear beginning-middle-end structure and making sure it has at least [i]some[/i] logical chronology to it goes a loooong way.[/list]

That being said, what I just wrote only really applies to specifically group RPs. I've not much interest nor experience in 1x1's, though I did, somehow, get a few hits on my rather poor attempt at a 1x1 check (can find it in my profile if curious). None of which went anywhere, mind, since I had no real chemistry with anyone who approached me, but it's an interesting footnote nonetheless. Wouldn't recommend taking it as a good example of how2intcheck though.