I have such a unicorn right now

. She's leaving in March to get married, and I'm hoping we'll be able to replace her.
We found her on Care. My suggestions are to really think about what the person will do -- what would a typical day look like? How often would she do childcare vs. errands and housekeeping?
The more clarity you can have in your ad and in your initial conversations with people, the happier you'll be.
In my case, we have a full time nanny, so I was hiring someone mostly to help with housekeeping and errands, to help me in the mornings before the nanny gets here, and to fill in sometimes. My unicorn is part time, and I pay her more if she does a nanny shift instead of a mother's helper shift. I was really clear with her that the job was mostly housekeeping and not child care. Anyway, she's fabulous, and I often wish she was our full time person!