The key to a good photograph is an obvious subject.  You don't want the viewer to work too hard to identify what they ought to be looking at in your image.  Short of Photoshopping in an arrow pointing to the subject there are numerous other tools to use as a way to encourage people to "look here first" - bright object on a dark background, in-focus object on an out of focus background, leading lines from the edges to a specific subject, etc.

One of the easiest tools is to simply have a single subject located away from any other elements that might conflict with it being the subject.  The eye goes first to elements that are out by themselves, probably as a way to simplify the pattern recognition in our brains.  I'm always on the lookout for these composition opportunities.

Not only does the tree stand out in a grass field by itself but the light hitting the right side increases the contrast between it and the line of trees behind it.  I increased the clarity (mid-range contrast) in the grass to give it more texture and to make the roll in the terrain more obvious as it passes by the subject.  I wanted it in B&W because it gives me more control over the tonal values without having to worry about the impact on color values.

It's a simple image but a good example of giving the viewer something to notice almost immediately with just a glance at the photograph.