To add lights to the model
As a general guide, the more lights there are in a scene, the longer it will take to render it photorealistically. For external rendered scenes, you may consider using the Standard Light Studio from the Recommended archive as a starting point, then strategically add a couple of Point and Spot lights around the scene. Point lights are good to light up a dark area of the scene, while Spot lights can add an element of drama and enhance realism.