With latest version of Adobe Photoshop Elements there are some cropping guided templates provided for users. Using these cropping templates you can get wonderful compositions without even thinking about the rules. It's just that you need to understand the right way of using these templatized cropping options.
Golden Ratio, Rule of Thirds and Grid, these are three cropping templates provided in 10th version of Adobe Photoshop Elements.
Here is a good link to better understand the meaning of these three rules - http://photoinf.com/Golden_Mean/Eugene_Ilchenko/GoldenSection.html