Go, Read: Chris Schweizer On Being Invited To Pitch
It looks like the cartoonist Chris Schweizer will be doing a short series of voluminous posts on how to pitch graphic novel work, which starts here with nuanced advice on how you need to be invited to pitch and that what we might consider an opportunity to pitch is really best used to familiarize the publisher with your work by presented completed work. It makes more sense when Schweizer writes about. I'm sure there are a million ways to go about this kind of thing, but Schweizer's advaince is practical and hard-won and at worst I would think might be worthy of running by your own thoughts to see where any might clash.
The one positive I can give you is that I think comics does a pretty good job of finding talent and giving it an opportunity. It doesn't away find a place for every talent arguable at a level where they could be published, or bringing that person or their project success once out there, but I don't know of a lot of people that didn't get any chance at all where I've seen stuff later that demanded better treatment without any conceivable reservation.