How did Adrian create his amazing rhino composition?
Always shoot the subject with light that will match the background of the images you want to use, or choose stock photos that have a similar tone as not to jar.
Select and place your characters into a scene with your favoured selection tools, and then adjust in order to make sure that they line up nicely with their new background.
Realise that light is bouncing and that different material bounces light back and understand reflections and different colours. Make lighting and colour adjustments with brushes at this stage.
Finally, with the image nearly complete, use the Dodge tool on the lighter aspects of the photo and the Burn on the darker aspects.