Yes, congratulations, Mollie! I second the RAW + JPEG option. It doesn't take that much more space up, and believe me, I've had some photo shoots lately that would really have been ruined without the RAW. But you can just keep the JPEG if you like it, and file the RAW file away to work on later. They are really very, very easy to work with!
I don't have a lot of tips, and Donita's is great advice. Black is a great color for newborns, it softens so well as a background and highlights the baby's creamy skin.
Maybe someone else will jump in, but I'm sure you'll do fine, you take absolutely stunning pictures all the time!
And have fun.
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Sarah
Equipment: Canon T2i (550D) with 18-55mm f/3.5-5.6, 55-250mm f/4-5.6, 50mm f/1.8, and 400mm f/5.6L lenses
Software: Windows 7, PSE 10 (Editor), PSE 6 (Organizer), and PSCS 4