Louis du Mont writes:
Sometimes an CG environment can seem too small or toy-like. A good way to solve this is to add an element to help the viewer appreciate the relative scale. In this video we're going to look at how to do this with a distant flock of low-poly birds.
If you're an advanced Blender user you can view the ~1 minute version here:
If you're looking for a step-by-step, then look no further: