The most straightforward rendering environment is one single, clear subject filling your view port. Before you fill your view port, with one single image, you should consider if the surroundings are critical to the view, or its design. If you need to fill your frame right up to the border, with a single subject, you might run the risk that the eye may feel uncomfortable concentrating on points falling particularly near the edge of the render. If often needs - or at least benefits from - a little free area around a subject to be able to move without feeling constricted.