I have a customer who has a very, very dark room that she wants to take portraits in. I'm photographing a 2 month old baby. What type of lighting should I use?
We take photos with light. You can't take photos in a very dark room.
The usual approach for babies is to bounce the flashes off the ceiling (if its white). This gives a nice soft light.
These photos of my grand-daughter were taken with three small strobes/speedlights bounced off the ceiling.
...first, you didn't say what kind of mood you'd like. Also, you left the question quite general. Hence I'll try to give you some general tips:
Good luck and good light!