A.J.
My first son was 4 years old before he understood the blowing out his nose concept. I think I tried everything and it just didn't work.
My youngest started blowing his nose properly shortly after he turned 1. It was very strange to see him do this but in retrospect he sees everyone in this house do it so much I guess he just wanted to do it too.
Patience. That is just about the best advice I can give. But once they get it, it is so nice! I can't stand runny noses!
A.