hmmm water is one the hardest things to pixel (along with glass ice and light streams), for the water you have to make it wavy or it looks bad... let see in order to make the sky don't use the spray brush... it is your enemy. use the line tool, fill bucket, pencil, paintbrush....ect., do the sky first so you can "lay" the sun on it, and you don't have that random purple spot between the sun and spray of colors, i see you only used the basic colors, use better colors those colors are so bright that the image looks like day light, i suggest using colors from the picture your using for reference, it saves time... well good luck hope i was helpful