Well, one rather generic technique that I do use a lot for indoor flash photography at events is:
- Manual exposure
- ISO as acceptably high as possible
- Shutter speed around 1/40, or the minimum necessary to ensure no motion blur of subject
- Aperture as acceptably close to wide-open as possible
- External flash in full auto metering
- Flash exposure compensation to taste, usually around +1 or so for ETTR
- Flash set up for bounce, with an omnibounce or other diffuser, colored close to the ambient lighting (usually yellow/gold) (make sure the ceiling isn't a nasty color first!)
- Auto white balance, with a sample greycard shot for reference in post (very important)
The automatic flash metering then acts as your "4th parameter", filling in whatever's necessary to get the exposure up to where it should be, whereas the shutter speed, aperture, and ISO are all set up to maximize the use of available light while still maintaining image quality.
The shots look more natural as there's less reliance on the flash, and the flash is bounced off the ceiling so it's coming from a natural direction instead of head-on. This technique also uses less flash power than relying on the flash as the primary lightsource, so the batteries last longer & it recycles faster.
The drawbacks are that you need to get the flash color pretty close to the ambient or correcting the white balance is pretty rough (even if you use a greycard) as the two lightsources aren't the same color, and your aperture is close to wide-open so proper focus is critical (less so with a wider lens though).
I really like this setup with my 20mm Color Skopar set to hyperfocal at f/4; I don't even have to bother with focusing or zooming at all & can completely concentrate on framing & the environment around me.