Make the spout wider and more pronounced, with more of a throat below the lip.
This one's from about 10 years ago:
When I was trying to figure out pitcher spouts way back when, I threw 6 pitcher necks (about 4 inches tall) and pulled 4 spouts out of each one. By the time I got to 20 I had it figured out pretty well. Then I wedged all that up and threw some actual pitchers.