Actually, I'm not a big fan of macro ring flash at "normal" macro or the most commonly used magnifications. To me, even with multiple light sources that can be individually adjusted offered by some ringlites, they just give too flat and "scientific" lighting when used for up to around 1:1, maybe 2:1 magnification. I do like a ringlite for higher magnification work (higher mags than most people do and higher than most lenses are capable of doing on their own).
I prefer using a twin flash (such as Canon MT 24EX shown below). They allow more flexibility... a greater difference or lighting ratio between the main and fill lights.

The flash heads on the twinlite shown are mounted on a Lepp/Stoboframe dual flash bracket (no longer made, unfortunately) instead of the the mount Canon provides, which is shown separately in the photo and clips onto the front of Canon macro lenses (different sizes are needed for some lenses... flash comes with one to fit 58mm filter thread lenses such as the 100/2.8 USM/non-L/IS). I prefer the Lepp/Strobo bracket because it allows a whole lot more separation of the flash heads as well as a lot more flexibility positioning them.
However, you don't really need to go to the expense of a macro flash at all, unless you really want to.
A single speedlite can do quite well... For example, all of the images below were done with a single 550EX (setup very similar to the 580EXII shown above):
In all three I used the 550EX on an off-camera shoe cord. I think in all three I also used a couple layers of white gauze bandage over the flash tube, held in place with a rubber band, to reduce the flash's output and diffuse it a bit. This acts like a large softbox in the sky, to smaller subjects like these.
The two praying mantis shots are more "full flash" (so that the background would go black, it was a rather busy tangle of leaves). Using a single, slightly diffused flash like this, the light tends to bounce and "wrap" around, so I didn't need a second fill flash. It is possible to use a second flash (with an optical trigger or something like that). Or, it's possible to bounce some fill off a white card or metallic reflector.
The flash was handheld fairly high and off to one side to simulate natural lighting, yet give some nice shadows. Camera and lens (100mm macro) were also handheld, but resting on an unside down, empty 5 gallon paint bucket.
The garden spider was lighter fill flash, to retain the background. No bounce and the flash was held to more directly throw light onto the subject. Camera and lens (70-200/2.8 with 25mm extension tube) were on a tripod. I am not certain I used the gauze bandage trick on this image, since it's fill flash. I might have used the wide angle panel instead.