Sun stars appear when the sun is just exposed behind a hard edge and you use a small f stop. Sun stars are strong compositionally because they are bright, colorful and interesting. Here is an image from Namibia:

This kind of image gives you a few moments to get it right. You can move your position up or down (depending on which way the sun is going) to reset the sun for a second or third attempt. Get something interesting in front of the sun. Arches work well. Trees also work well, as do horizons. Since you are shooting right into the sun beware not to look at the sun with your eyes (not even through an optical viewfinder). Mirrorless cameras work well here since you are looking at a screen (monitor viewfinder) and not the sun itself.

          Exposure of sun stars are tricky. You are shooting right into the sun which is very bright. If you set the camera on a small f stop to create the sun star and you use a fast shutter speed (because the sun is really bright and you do not want to clip it) then the foreground is typically very dark. Graduated neutral density filters will only help you if the sun is on the horizon. If the edge you use to create the sun star is a tree or an arch like this image graduated neutral density filters don't help because they just turn half the tree or arch dark.

          You may have to bracket at different exposure values to blend your images later. I prefer not to do this if I don't have to. I still bracket my exposures. Then I open up my images on the computer and choose the best exposure that allows me to recover the clipped highlights AND push the shadows brighter. This typically works very well especially if your camera has good dynamic range. This image is processed from one single raw file. Shooting images at settings where you have no clipped highlights may not work because the dark part of the image may just be too dark to work with. So some clipping is okay as long as you have bracketed images to choose the right one from.

          I hope you go out and try some sun stars.