Found this interesting and very useful article by Erez Marom about composition basics in macro photography via dpreview.
“It’s hard to overstate the importance of composition. For all of the emphasis we as photographers tend to place on which camera, lens or other gear to use, there’s nothing that contributes more to a pleasing image than careful attention to the framing of your subject. In this article I’m going to discuss some of the compositional techniques most applicable to macro photography. I’ll illustrate these with a lot of images, as these concepts are often much easier both to understand and apply with visual examples in mind.”