Composition is so important, but there are no rules to help us. I do more painting than photography, and am always altering things to change the composition - oil paint allows you to do this. The horizon goes up, then it comes down. I paint a tree out, then re-instate it somewhere else in the painting. I add some people, then move them. And so on. Finally, when I think the painting is finished, I frame it and hang it on the wall. And next day I realise that I need to move a fence-post half an inch to the left....
Alan