I shot in a venue yesterday where the light was going to be speedlights off camera, using light stands and umbrellas.
In the event, it was not possible to bring in lights, so I had to use one on camera flash. And here’s what I got:

I bounced my flash behind me. Up and behind me, but down enough to ensure that I hit a white wall, and that we get catch lights in the subjects’ eyes. And using TTL flash. And with flash compensation set to +1 to +2 stops.

And that gave me ok light!