Find time to talk to parents singly and collectively.

This was not one of my strengths.  I didn't always find the time to meet with them collectively.  Because of my conviction that the youth and I needed to work out our own issues without running to the parents, I didn't always bring the parents in either.
However, parents need to be kept informed.  If you meet with Parents collectively you can answer all questions at the same time rather than the same questions time and time again.  It also helps if they all hear the same things at the same time, so if there is a misunderstanding, other parents can straighten them out.
Individually, it is instinct more than anything, but if there seems to be something the parents don't know but need to know and it is not betraying the youth, then meet with the parents.  It may be that the kid is much better than than the parents are giving him/her credit for.