Most times, when I pull out my flash, I'm shooting impromtu, informal shots of my boys. Here are a couple examples:
But The Family Photojournalist is about more than just portrait documentaries, though this is certainly a reasonable aspect of it (see Steve McCurry's head shots of Afghanis, etc). Flash can be used to light or augment your subjects in a very pleasing way. One negative is that the burst of flash can draw attention to you, but if you are careful with your compositions and take your time getting the shot, you shouldn't be firing away every few seconds anyways.
First, let's discuss bounce. Shooting on-camera flash is usually frowned upon and for good reason. It's flat and dull. Anyone with a point and shoot can do this. You bought an SLR, why not enhance them with flash instead of kill them? By bouncing your flash off a side wall, for instance, you turn your living room wall into a giant softbox. Example:
This shot was taken by bouncing my canon 580 exII off of the far wall, directly to camera right (which is about 15 feet away). The quality of light improves dramatically, rendering a softer, more pleasing light on your subjects. Also, by bouncing it from the side, it shapes my wife and son's faces nicely. By shaping, I mean that it creates pleasing shadows which outline the face and add a more 3-dimensional aspect to it.
Side note: Light modifiers have their place but if you can find a place to bounce your flash, you won't need a modifier (I never use one).
Here's another using side bounce off our front door, which is white:
Flash is also great for shooting in your house at night. Overhead lights cast those raccoon shadows. By bouncing flash, you get to choose the quality and direction of the light. In other words, you decide which direction your light is coming. Instead of overhead or from a nearby lamp, it can come from the side, from 45 degrees up, etc.
My usual settings will vary depending on how I want the image to look but generally, I'll get an ambient reading and then underexpose between 2/3 to 1 2/3 stops and allow the flash to fill in. This keeps makes the flash the main light but allows some of the ambient light to remain. The more you underexpose, the more subdued your ambient light will appear. I usually use full evaluative metering mode and overexpose the flash exposure by 2/3 to 1 full stop. Remember, though, that flash exposure works the same as a camera meter (exposing for neutral gray) so consider if your scene is mostly light or mostly dark which will change things.
Things to consider when bouncing flash:
1. lighter walls are preferred-colors such as white, light blue, yellow, and even tan provide a good bouncing surface-darker colors will eat up your flash
2. be careful of white balance when bouncing-if you shoot black and white, as chuck and I often do, it won't be much of an issue but if you're shooting for color, your flash will take on the color properties of the wall itself (and it's tough to fix)
3. watch the direction of your bounce-you usually can't go wrong when pointing the flash directly to the left of right-avoid pointing it straight up at the ceiling, which results in shadows around the eyes (i.e., raccoon eyes)-you can even point your flash 45 degree up and behind you (which allows you to use the ceiling but the light does not hit the subject from directly overhead)
Here's an example of the 45 degree flash position (I actually used this same 45 degree position to light the shot below):
4. if you don't have a wall, look for something to bounce flash off of-it could be someone's white shirt (that they're wearing), white furniture, window blinds, etc-try this sometime, you'll be surprised that it works (esp. when you don't have another choice)
5. experiment-learn how to use your flash-you can read all you want but if you don't slap on your flash and use it a bit, it won't be worth using when you need it
I wouldn't recommend one flash brand over another for family photojournalism. I use Canon professional flashes since I shoot professionally as well. It makes sense for what I do. There is also the Sigma DG series (which i used to own and liked), Sunpak series (which i've also owned), and others. The important thing is that your flash has E-TTL capabilities (meaning, it can sync with your camera which helps it determine how to properly expose the shot) and has tilt and swivel capabilities (for bouncing flash off stuff).
One other benefit of using a hot shoe flash is that it provides an AF assist beam, which helps the camera focus in very low light. You can get focus on something in near darkness with that beam and that can come in very handy.
Even though this shot has been posted before, it's the only shot in the birth series that used flash and I felt it was appropriate for this post.
I hope this has been useful. Please send us emails if there are things you'd like to be explained better or want us to go into more depth. I don't plan to go into technical stuff like lighting patterns, etc., but I'm glad to help you via email if I can. Your thoughts and ideas help us shape upcoming posts and the emails we've received so far are greatly appreciated, guys.