A well-placed word is (usually) more powerful than a whole paragraph of descriptions.
Write a full scene (dialog, etc., and at least four paragraphs) between a man and a woman who run into each other at the wedding of a mutual friend.
The man intensely dislikes the woman. Can't stand to be around her. Describe how she looks, how he feels for her through his dialog, and color everything with his feelings for her.
The woman loves the man. Craves being around him. Describe how he looks, how she feels for him through her dialog, and color it with her feelings for him.
Girls must write from the view point of the man.
Guys must write from the view point of the woman.
Rather than give a full paragraph of description, learn to use a few carefully placed words. Also, getting into the head of the opposite gender is a great exercise, and can be very entertaining. :-)
Let me know, in the comments below, how it goes!