One thing I've noticed that really seems to help the overall technique is keeping the fish underwater, in a well-oxygenated environment until the absolute last second before taking the photo. This seems to give three distinct benefits.
1. Often times the dorsal spines will "spike" which seems to give the fish a more lively appearance.
2. The colors of the fish will be more vivid, which greatly enhances the photo.
3. The fish releases in better condition, which gives you a chance to catch it again later!!
People like George have long been advocates of finding ways to keep the fish lively and vibrant during their brief trip out of water. This always yields a better photo.
