Easiest way I would think to describe retro-haling is, put your lips together, and breath out through your nose while you close your mouth the rest of the way. Then you don't have to think about pushing the smoke back, just a natural closing of your mouth while breathing out through your nose will push the smoke back, and then it will get picked up and sent through your sinuses.
When I do it with cigars, I tend to blow out about half of the smoke or so normally, then retro-hale the rest, basically just finish off the exhale through the nose, otherwise there is just too much there. I find I notice more detail in the flavors that way. Pipes have much more subtle flavor, so it may not be as helpful to exhale most of it first.
When I do it with cigars, I tend to blow out about half of the smoke or so normally, then retro-hale the rest, basically just finish off the exhale through the nose, otherwise there is just too much there. I find I notice more detail in the flavors that way. Pipes have much more subtle flavor, so it may not be as helpful to exhale most of it first.