Sun stars are tricky and also are dependent on the particular optics of the camera lens. In general they show up well in wide angle lenses at the smallest aperture. This one overwhelms the photo. As I mentioned in the field, if you can position yourself to the sun is just peaking around the edge of a tree trunk it will reduce the amount of light hitting the camera and will reduce the size of the flare. Your second sun star photo offers a nice example of this.
Fun to play with capturing blurred water. This exposure looks like it was around a 1/10 of a second. A tripod will help significantly. When you are hand holding something like this I would fill the frame as much as possible with the water. It is the more interesting element anyway, but then you have less "still" subject matter that is blurry from the slow shutter speed.
