Camera and Setup

Take a lot of photos - Children's expressions change in an instant. Sometimes I take upwards of 30 photos for the same pose. If there are multiple kids, pay attention to each kid and make sure you get an expression you like from everyone. You can always composite the photos later (see next tip).

Composites - With multiple people in the same photo, it's sometimes really hard to get a usable expression from everyone. If you follow the above tip to take lots of photos and get at least one usable photo of everyone, then you should be able to make a composite in Photoshop. If the photos are from the same pose in the same lighting conditions, a composite should only take a few minutes once you know what you're doing.