for punggol beach, either you have to find a very nice arrangement of the scattered rocks - which is hard unless you manage to find a good high viewpoint, which i haven't..
or you just leave them out altogether. another way is to go close and shoot WA with a few rocks arranged nicely dominating the foreground.
this one here, the rocks are cluttered, hence composition is messy, and it does not work. also, color palette is pretty weird for a sunset shot. try experimenting with WB post or in-camera to get more pleasing colors (though not too off, the sun should still be whitish/orangish).
personally here i would have tried a telephoto perspective and done the sun with the boat.
other than that, i wonder why not many people go all the way to the end of punggol beach, there are a lot more possibilities there than the usual places, which is probably about halfway.