I love working with children. They have a freedom in front of the camera that is gone by the time they get older. Its an unselfconsciousness which is a pleasure to photograph. Babies, of course, have the same unselfconsciousness but they can sometimes prove more difficult to photograph.
Babies older than 6 months can be coaxed, easily entertained and gently manipulated to get the expression or position that you need to capture a great photograph. But when working with small babies not only can you not get them to "do" anything, you also have to work entirely to their schedule. The thing you need to remember is that photographing small babies takes more time, because you just have to let them be.
When I work with small babies I always take more shots than usual. Mostly because it is more difficult to capture the perfect expression. Babies make a lot of funny faces!
Oh and don't forget the detail shots. There is nothing more precious that those tiny fingers and toes! I love to capture these in relation to the other family members too - just to get a sense of exactly how small they are!