Whenever possible, make note of the relative scale for scene and subject, as well as the presence of lens effects. When photographing the scene for your composite, do you plan to use a polarizing filter to remove some glare from a reflective surface in the image? Will you need to repeat this type of glare with your subject? How much distortion will happen due to the size and type of lens? Would other ambient factors throw a certain light or look onto your chosen subject? Don't let the details get away from you. Ultimately, they will sell the illusion of your final image.
Dan Moughamian has a background as a fine art photographer and creative imaging specialist. Scott Valentine has a deep knowledge of lighting, optics, and 3D modeling. Both are Photoshop experts.