When writing the issue essay, be sure to summarize for both sides of the argument in your introductory paragraph and also briefly summarize both points of view in the concluding paragraph.
In the introductory paragraph, you'll want to summarize both sides of the issue so that the second, third, etc. paragraphs can follow logically. As is the case during effective arguing, you'll need to acknowledge the views and opinions of the opposing side so that you can address those opposing views. An essay in which you clearly present your case is surely a good essay, but an even better essay is one where you not only can clearly express your own opinion, but where you can also anticipate any objections that may be raised by somebody with differing views.
Likewise, in the closing paragraph, you'll want to briefly restate the main points from your introductory paragraph, being sure to cite both sides of the arguments. However, in the closing paragraph, only a sentence or two at the most is needed to effectively address the oposing view. In your closing paragraph, you should focus on your argument and reiterate the evidence that you have presented.