Emphasis

Focal point- The point of interest. The main point on the image.

.. 2012. DeviantArt. Web. 5 Dec. 2012.
<http://namisis.deviantart.com/art/--338003379?q>.

In the image above, the main focal is the creature's head in the middle.

Isolation- Extra emphasis to a certain character or object by using value.

1. 2012. DeviantArt. Web. 5 Dec. 2012.
<http://cheo36.deviantart.com/art/1-340416336?q>.

In the image above, it could be argued that the structure in the background is the part that is being emphasized by isolation simply because it is brighter and more detailed. But, the character in the foreground could also be the part that is being emphasized because it is closer to the viewer and darker. Your eyes are drawn to both parts.

Placement- Placing the main subject in the center of the piece.

Amaral, Leonardo. Pescossaur. 2012. DeviantArt. Web. 5 Dec. 2012.
<http://ltramaral.deviantart.com/art/Pescossaur-340460237?q>.

As you can see above, the focal point is the creatures head, which has been placed right in the middle of the piece.