Rule of Third Cropping

1. Edit>Preference>Guides, Grid & Slices >Grid enter 33.3 in Gridline Every Field
2. Then choose percent on from the pop up menu on the right, change the default setting from 4 to 1.
   
3. Click [OK].
4. View>Show> Grid.
5. Return to your Image.
6. Press V to switch to MOVE tool then position the image on your desired location.
7. Crop image.