AJSchumacher's got good advice. I'm in the process of trying to get a graphic novel to trade publishing, but I've also been published in the direct market. In my case, I pitched my script with an artist attached, but I find that since a lot of editors/ agents may like the script but not the art, I suggest you commission an artist for prelimnary designs or one or two key pages under a WFH deal ( with appropriate pay of course), you may want to specify that the art isn't final. That way you're flexible if only the script gets liked.