The biggest “trick” to ensuring a healthy working relationship for everyone involved? Communication. Talk to each other in great detail both before the commitment begins and during the employment contract as well. It’s the only way you’ll both be on the same page, and it will iron out any misconceptions before they can even occur.
This goes without saying, but there needs to be a clear-cut set of instructions, rules, and/or guidelines that give details on what’s expected of everyone in the family (not just the nanny).
Behaviors and discipline efforts need to be addressed up front. Schedules, routines, and any things or areas in the home that are off limits should be outlined as well. You can’t expect your nanny to know you planned to dress your kids in that outfit on Sunday if you didn’t tell her not to use it. Nannies aren’t psychic.