There is more than one right answer. I like to show a lot of ambient light and use the flash to emphasize my subject, so often use the following steps.
I start without the flash and find an ISO/Aperture/Shutter that works, generally I start with Aperture and go wide open. Then I set a shutter speed as slow as my subject and shaky hands will accept (with stationary subjects and not long focal lengths around 1/30-1/60). Now I take a test shot, if everything is black (I check the lens cap) I start walking up the ISO. If I am over exposed I lower my ISO/increase my shutter speed.
At this point I am not going for a perfect exposure, just making sure that my background is not a black cave (generally 1 to 1.5 stop under exposed).
Now turn on the flash, choose a bounce surface and fire off a shot -- check exposure on my subject, too dark increase flash power (or ISO), too bright decrease flash power (or ISO).