Space to look
This is used especially in portraits or pictures with people. Leave a space to watch means that if the subject you are photographing is looking to one side or the rotated side to side, we should leave a space on the opposite side of the picture.
Thus, if the subject is facing left should put the subject to the right of the picture and leave a space on the left. Why is it advisable to do this? Because when a person looks at the photo, it will follow the line of sight of the model. If you do not leave a space is to create tension.
Need not be much space, but if enough so you can follow the line of sight without feeling that stops abruptly.
Here is a shot where I leave empty white space to the left of the model that allows us to look without a sharp cutoff. The model is looking to the left so we will continue to look to that side.
In this case I cut the photo in Photoshop to see the difference with the same photo. Look like there is no space creates tension in the image and you have the feeling that something is missing, we do not know looking at the model or where it is looking. Even this image produces a feeling of suffocation.
This in no way means that you can not make images and to create tension. Remember that all rules are broken. But there must be a reason and must be a conscious decision
