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This is what I do. I don't know if it is the very best technique, but it does work pretty reliably for me. For indoor shots at night, such as at a wedding venue, I set my ISO at 400 or 800, the mode to Tv and the shutter speed to 1/60. I take a couple test shotsI I want the exposure without flash to be 1/3 to 1/2 stop underexposed. I then test with flash, no compensation used, in TTL mode. I use a flash bracket with a rotator to get the flash directly over the lens in both portrait & landscape positions. I use a Lumequest 80/20 and bounce the flash off the ceiling. About 20% of the light will bounce forward and strike the subject. If the ambient light is tungsten, I may put a full or half CTO gel over the flash and set the white balance to tungsten. If I have done this successfully, the combined flash & ambient light looks like that is the light in the room. It does not look as if flash has been used at all. Shadows are open and there is no difference in exposure between near and far subjects in the same frame. Contrast is low and the unpleasant micro-contrasts you would see with direct flash are absent.The purpose of the bracket is to have the shadows fall below & behind the subject if they are near a wall. It puts a small shadow under the chin and it is better if the flash is not too far above the lens and that the chin shadow is well filled (meaning that the ambient light is close in value to the flash light). If the light is too high or the shadow too dark, the subject will appear bearded. The flash bounced off the ceiling will fill the room with light of the same or similar color temperature as the ambient and smooth things out. Problems will arise if the ceiling is off-color or too high. A few tests usually suffice so that all the rest of the photos taken that evening match pretty closely. There will be some minor variation but usually RAW processing will correct it without much trouble. The addition of the gel is important as it brings the color balance of the flash and the ambient close together. Best results will come with a lens f/2.8 or faster. Slower lenses will require higher ISO (and noise). Faster lenses make for quicker autofocus, too. I try to keep the ISO below 800. This will match shots taken earlier where there is window light in the room. If you use the gel the shots will match pretty well. Without it, the background will appear quite orange and won't match earlier photos. There will also be a color balance shift between near and far subjects in the same frame. This is usually NOT attractive. Instead of Tv mode, you can sometimes get better results using manual. In that case, set the lens to 2.8 and shutter to 1/60 and the ISO to whatever will give you a 1/3 to 1/2 stop underexposure without the flash. I've also had good results using 2nd curtain sync under some conditions. Some colleagues I know will use slower shutter speeds than 1/60 but I've been burned by camera shake a few times and I'm reluctant to do it. Once again, set the flash to TTL. This will work better if the room is pretty evenly illuminated. Hope this helps. I don't know if the is 'best practices' but it does work for me.