For quick indoor shooting, the simplest and most effective way to soften a hot-shoe flash is usually to bounce it rather than fire it straight at the subject. If you have a reasonably low white ceiling, aim the flash upward and slightly behind you. That turns the ceiling into a much larger light source, which makes the light softer and more flattering than direct flash.

Bouncing straight up can sometimes create uneven facial lighting or deep eye sockets, so the slight backward angle often looks better. Bouncing off a wall can also work, but it’s usually less consistent because the distance to the wall changes more than the distance to the ceiling.

The key idea is that softer light comes from a larger apparent light source. A small direct flash is harsh; a ceiling used as the source is much bigger.

If your goal is maximum efficiency or reach, direct flash puts more light on the subject, but it will usually look harsher. Small diffusers alone generally won’t make the light as soft as bounce does.