Old thread but... other people may find this helpful and interesting in case anybody is looking to go beyond the initial thumbnails concept art. These are some cool storyboards from the animated show Kim Possible. Of course storyboards don't have to be this well done as these are professional storyboards however there's still loads you can learn from them. :)
http://www.deviantart.com/art/How-To-StoryBoard-Kim-Possible-415794403
Its more partial to animation but the same concepts can be applied to comics as well.
