When I worked in Mother Baby as a tech, my main duties were catering to Mom and getting vital signs. Catering duties include: making sure she is comfortable, making sure she isn't hungry, making sure she is not sleeping with the baby, answering any questions she might have, amongst more. A lot of the time I helped moms up to the bathroom the first time they went to the bathroom. We got to remove foleys on my unit as well as draw blood and do blood sugars on both Mom and Baby. If Baby was crying a lot and I could tell the parents were exasperated, I would either offer to take Baby to the nursery or help with Kangaroo Care. I also helped parents with bottle feeding their baby. Moms who had c sections needed their Peri pads monitored for bleeding as well as post c section vitals.
I wasn't in the nursery very often but when I was I'd bottle feed babies, hold and rock some of them who were crying, give baths, draw blood, and change diapers.
It's been a couple years since I had that position but I guess the best tip I can give you is to show your enthusiasm. The Mother Baby infant in my experience is very different from any other unit in that situations are usually happy. Being enthusiastic, and showing your kindness and patience will help in your interview. Good luck!