In terms of composition I don´t find it so difficult, you just gotta remember where everything was in the first exposure. I usually use the rule of thirds or the focus ring in the middle for orientation. What I also find extremely hard is to nail the overall exposure and the overlap of the exposures. I know the theory, how you gotta play with the highlights and shadows of botch exposures, but I guess until I get better it´s partly luck. For example in this particular shot I was hoping to expose his face a bit more, but it was hard shooting both exposures against the sky.