Working with kids is tough enough, but working with kids and their families can be quite hard. And to be honest, any time you're working with kids, there's always interaction with the families: they want to know how a class might have gone or whether their child is reaching developmental milestones on time.
When I'm working with young children, I work to foster a relationship with the parents that acknowledges that at the center of a child's education is their family. My role isn't just to teach someone's child but to work with that family so that they may continue to educate the child and seek further enrichment opportunities.
There are many ways to do this, but I've done one thing almost ubiquitously: talk with them.
It might be tempting to unload one's "expertise" on a parent, but rather, I work my hardest to convey my love of a parent's child to them. I've often relayed an anecdotal story to parents - "oh, your child is so cute, they keep putting boxes on their head and screaming 'I'm invisible!'" - only to have been met with "Oh man! He does that here too?" I show parents that I'm paying attention to their child and that I see sides of their child that are only visible in an intimate relationship. That same parent is much more receptive to my suggestions when it comes to follow-up educational opportunities or even activities that one parent might be able to do at home to expand their child's learning.
That may be simple, but it's the best advice I've ever gotten. Most interactions with parents are bearable when everyone has established that the child is genuinely loved and cared for.