I took my mother in law with me to register, but anyone who already has children will be a big help and be able to provide guidance.
A friend just had her baby, what I've observed over the last week is:
the pack and play (as a changing table)
diapers and wipes
bottles and formula (even if just as insurance, you want to be able to supplement without any drama and hassle if baby is hungry and breast feeding is a struggle)
You don't have to be prepared for the whole infancy on day one, just the first few weeks. :)