Andrew Hoyle has a terrific tutorial article on Cnet on how to take macro photos on your smartphone using a macro lens. The article includes tips on how to use Photoshop or other image editing software to improve the images. The lens Andrew recommends is pricey ($265), but he has links to cheaper lenses that would probably be good enough for a slacker dilettante like me.
Andrew also recently posted a video tutorial on backyard macro photography using a SLR camera:
Image: Copyright Andrew Hoyle, used with permission