I've taken the GMAT twice and used the same approach both times. The first time, I got a 6.0 AWA, awaiting official results for the second.
Both times, the prompt was something along the lines of "Pizza good, so people should eat as much pizza as possible."
My first paragraph discussed 2-3 reasons in support of the prompt. "It's true that pizza is delicious and is an important source of nutrition, etc."
Then my second paragraph introduced some counter-points against the prompt. "Past a certain point, pizza's high caloric content outweighs its benefits..."
Then I summed it up by saying "While there are several reasons why eating some pizza is good, I disagree that people should eat as much pizza as possible."
I hope my overly simplistic example helps.