There are some parents that I remember, I think because I see them often enough or they might be particularly unique looking (to me, anyway). There seems to be some mental bar that needs to be crossed before I can reliably recognize them, otherwise they all kind of blend together for me.
The characteristic doesn't have to be particularly representative, but the more extreme / emotional, the more effective.
E.g. remembering "Jim always has perfect Ron Swanson hair" helps in making the name itself memorable
I have to write down the name of everyone I meet in a day and review it before I go to bed in order to even have a chance.
Plus, I have a paralyzing fear of using the wrong name so I don't practice that often unless I'm completely confident.
It's like numbers. I remember IP addresses and breadcrumbs better/longer than I should, and why is obvious (sysops, web dev, nerd?)
To be honest, I learned this tip when I worked at a large international organization, and I needed to familiarize myself with a large number of new people quickly.