The most important thing you can include in your pitch bundle?
Previously published work.
Seriously.
Why should I (as a metaphorical publisher/editor) risk money on you if you've never done anything? Even if your pitch rocks, you're still a nobody.
Assuming this is a straight pitch with no talent attached, I have to pay for art, pay for printing and marketing, possibly even distribution. Why should I do that on your work, when in all likelihood, no one will buy it because no one knows you?
Beyond that, I wanna see that you can write (I don't mean specifically in script format either). I wanna know you can follow the instructions I gave for submissions. I wanna know what makes YOUR story so special. I wanna know that you can actually lay out a story from start to finish (and I DO want to know how it all ends, because if you try and sell me a teaser, I'm sliding it in the round file beside the desk).
Most of all, be fast. I don't have time for this, so make the time I set aside to look at this worth it or I'm just gonna be irked.