People who merge multiple photographs will generally nail down the white balance across all the images, as well as the exposure. This can be done in-camera if you're shooting JPEG or in post with the right tools. This might not produce *pleasing* colors, but should allow the stitching to succeed with cleanly merged colors. Then paint in local white balance adjustments as necessary to get pleasing color.
As for composition, well, having been digging around in this pretty seriously for a couple years now I find that photographers are insanely poorly served by their resources. Everywhere you look it's idiotic stuff like "Rule of Thirds" and "Horizontal Lines Convey Peace" and nothing about, you know, actual composition.
Henry Peach Robinson's "Pictorial Effect in Photography" (available free on books.google.com) is a nice relatively compact book on photographic composition. I was sufficiently frustrated with the state of the art to write one as well, which you can find by going to my blog and looking. I refuse to plug my own schwag in any but the most indirect fashion, and anyways Robinson said it all better.