u shooting manual mode?
the basic rule is..
shutterspeed controls the ambient, aperture controls the flash.
off camera flash can be a challenge... i'm only a few weeks in but slowly getting the hang of it, but i'm far from expert
u got a d80?
dont forget that you can use the in camera flash exposure compensation to adjust flash too.
typically i work with closed down apertures and slow shutterspeeds in the dark, this helps get over the difficult to focus hangover, and also allows a bit of room for easy adjustment if i dont like what the flash is looking like.
the flashlight idea is a good one.
check out my fiftytwo on flickr.. all (3) have been offcamera works so far.