In the world of computer graphics, you can do anything. Your cameras can fly through the air with the greatest of ease. You can put lights anywhere and point the camera right at them and not see them. But when you do that with reckless abandon, your eye starts saying to you, even subconsciously, “wait a minute, that looks fake.”
Sometimes, realism is greatly enhanced by paying attention to the techniques and inherent constraints of physical movie-making. Such as the following …
Camera dollies, booms, and trucks: The lightweight hand-held digital “steady-cam” is a very recent invention. Most of the time, cameras are mounted on tracks or at least are pushed around on rubber-wheeled carts, normally in straight lines. If the camera is elevated above human-head height, it’s mounted on a crane, which lifts it up in a circular arc while the camera at the end of the crane can pivot on two axes. The camera must zoom to follow the action, which causes subtle changes in the apparent depth of field (“foreshortening”). Your eye recognizes these familiar artifacts, even if you don’t know what produces them.
Camera setups, and Editing: Scenes are normally shot from one or multiple cameras, each one of which must be placed in a generally fixed position and so that they cannot see one another. The completed scene is “cut together” in the editing room. Consider doing the same thing. Blender has a great “preview-render” ability which can generate low-res renders very fast. Set up cameras, shoot your scene in low-res from each angle (with “frame markers” included), then try your hand at editing, using the VSE or a third-party tool, before you start to refine each shot.
Compositing and the Node Editor, “Digital Darkroom”: Often the easiest way to deal with a shot is to break it down into simpler components and to then deal with each one separately. The MultiLayer output-file format is specifically designed to capture all of the data generated by a render. In simpler situations, the Node Editor (your best friend!) still lets you break a shot down and to deal with it piecemeal. When a moviemaker has done his job well, a shot might look like “it just happened that way,” when the reality is that almost every shot most easily approached in a multi-stage process.