Babies
Babies are so stinking cute & babies are... well babies. They don't take direction, they don't care that there is a camera in their face,
and they can have good & bad days. 
There are two type of baby photos:
Newborn, which are considered 1-3 weeks old. This age is key because all babies wants to do is sleep, eat, and poo. At this age, they still like to be squished up and their skin hasn't reacted to the air yet. Over 3 weeks of age is a baby, not so much a newborn, baby should have a bit of a schedule so we know when they are sleeping & hungry, and of course we can still capture all the cuteness!
If you missed the newborn phase here are some other moments to consider... at 3 months they are smiling and reacting to everything. At 6 months they might be sitting up and a great milestone to capture. Older than 6 months I suggest a 1 year session.
Let's chat about your little babe and see what kind of session is best.