Here are a number of good sites on writing comparison essays.
http://www.google.com/search?hl=en&source=hp&ie=ISO-8859-1&q=writing+a+comparison+essay&btnG=Google+Search
What is a good way to begin a comparison essay?
2 answers
You'll find many ideas here.
http://www.eslbee.com/compcont.htm
http://www.unc.edu/depts/wcweb/handouts/comparison_contrast.html
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http://www.bookrags.com/articles/5.html
http://leo.stcloudstate.edu/acadwrite/comparcontrast.html
http://www.eslbee.com/compcont.htm
http://www.unc.edu/depts/wcweb/handouts/comparison_contrast.html
(Broken Link Removed)
http://www.bookrags.com/articles/5.html
http://leo.stcloudstate.edu/acadwrite/comparcontrast.html