RedRoxx44 wrote:However they do consistently fire with the camera flash and not with the sensor, so I guess that is good.
I'm not sure what you mean by this... Do you have light slaves and the flash from your on-camera flash triggers the slaves?
The best way to use off-camera flashes is with radio slaves, Pocket Wizard makes some good ones. The light slaves are crappy and unreliable. I suppose that's not so bad with cave photography since you've generally got several opportunities for a single shot (rather than sports photography for which they're more often used).
Are you using manual or auto settings on the flashes? It's difficult to get a good effect unless you can set them just like you would adjust the settings on your camera. Sunpak makes some good flashes that allow fully manual settings.
A good rule to make a subject "pop" with two slaves is to set one in front of the subject at an angle (not directly in front, this makes lighting flat) and one behind to backlight it. Set your camera's aperture and flash sync to that of the main flash in front of the subject. Set the backlighting slave one or two stops brighter than the front-lighting slave. This adds a strong 3-D effect to the shot and really makes it pop.