Ever since I got my SLR several years ago, I've been fascinated by the world of flash photography. Specifically, small-light, off-camera, multi-flash photography. Most of what I've learned has come from the awesome strobist website, where David Hobby goes through his methodology and theories for off-camera flash through a series of tutorials and behind the scenes explanations.
I don't use flash all that often, but when I do, I usually go with a simple one light bounced of an umbrella slightly off axis. It gives a nice, subtle shadow across the subject's face and can generally light up the entire scene.
The problem with off camera flash, is that it's really hard to setup quickly and even harder to move around (think chasing a moving child). My general preference for low light situations (mainly indoor parties) is to use my fast prime (50mm 1.4) and a higher ISO. This doesn't always work, so I tend to shy away from indoor photography.
Now that I'm beginning to consider branching out to photograph other people and their family, I really need to up my game and add a few more skills to my repertoire. The first one is on-camera flash photography and how to control it. I won't get into the details here, but you can see in the two picture above that one was with flash and the other without. Both pictures were taken with the same exact camera settings (ISO 640, F2.2, 1/80 sec), but the first picture had flash. It's not perfect (I'd like to learn how to get rid of the hard shadow under Noah's chin), but it's a lot better than the picture without flash.
I'm going to experiment a bit in the next few weeks, so hopefully I'll have learned something.