My iron tends to over shoot the heat setting when I first turn it on and I've scorched or melted many projects before I figured out this technique. This also works well for quickly changing heat settings from cotton to synthetic.
I use the burst of steam function which works like a charm to remove excess heat from the iron. Simple right?
I used to use a damp terry cloth towel as a heat sink but found this is much more effective and less messy. I still iron a damp towel to easily and effectively remove starch buildup though!