I strongly second this, and thinking making sure they have an outlet for concerns/ideas about career growth and other interpersonal, HR, culture or other "soft"

I strongly second this, and thinking making sure they have an outlet for concerns/ideas about career growth and other interpersonal, HR, culture or other "soft" things from time to time is important too. It's amazing how easy it is to go a year without bringing any of this up, only to have someone give notice when it could have been avoided through a few important if perhaps slightly uncomfortable conversations. I'd also make some room for praise, given in private and in detail.