My method for creating photorealistc 3D composites with Element 3D in After Effects:
Motion track the footage using 'The Foundry Camera Tracker' & create a "scene", afterwards toggle between 2D & 3D modes to locate track points on the "Floor" of your scene. Next place your 3D model on the surface of the floor; it should now appear as if your 3D model is "in the scene". The next steps will vary depending on your situation, but for this scene I then created two Lights, one was an ambient light to light the entire 3D model, the other was a point light which I placed on the far left of the model to imitate the sunlight from the window. The next step was turning on Ambient Occlusion within Element 3D & also applying a subtle drop shadow to the Element layer. At this point everything should be coming together, however the model will likely appear to be too "sharp" compared to the original footage. To solve this, turn on Depth of Field for your After Effects camera (this will take some tweaking to get the DOF of the 3D camera to closely match the actual DOF of your film camera.), also turn on motion blur for your composition & Element layer, I would also suggest turning the motion blur samples in Element up to at least 12 to avoid the "shutter" look. Finally apply the Tint effect to your Element layer & dial down the saturation to give the 3D model a more flat & realistic appearance.
Obviously there are numerous ways to achieve an effect such as this one, this of course is just my method.
Filmed on Canon 7D.
Software: After Effects, The Foundry Camera Tracker, Element 3D, & Fresh Food Pack (for 3D Model).