the headwaters are really blobby.
It's a totally minor thing taht nobody but a few of us perfection-obsessed cartographers will ever notice. But still, I sure would like to find a way to do rivers better in general. It's high on my "I suck at this" list.

I was looking at the Vaniya map, and the headwaters work well enough there, just as simple black lines thinning to sharp points. But that map has a particular style that lets a thick black pointy line work well. I don't think that's any kind of universal solution (which there probably isn't one of, anyway).