i have no kids, but my co-worker had a little girl last year and was freaked out about how to introduce them. She would keep them in the babies room with her while she was preparing the crib etc, they got used to the surroundings.
She also started sprinkling baby powder and ointments on the crib and surroundings to get them used to the smell as well as encoruaged them to put their heads on her belly.

When Nia was born she would agian bring them into the bed room with her while changing or feeding her. She also would let them sniff her clothes after the baby wore them, let them sniff the spit up rags etc.