Sarah has a nice introduction paragraph. The paragraph begins with a generalization about the topic of becoming a successful writer. Sarah has also included supporting detail sentences that narrow and focus the topic of the essay. In Sarah's introduction paragraph it is clear that there are three areas of good writing to be discussed in the essay: 1) the importance of background in grammar and vocabulary, 2) the writer's skills in writing essays, and 3) the writer's skills in editing.
1 Historical review: Some topics are better understood if a brief historical review of the topic is presented to lead into the discussion of the moment. Such topics might include "a biographical sketch of a war hero," "an upcoming execution of a convicted criminal," or "drugs and the younger generation." Obviously there are many, many more topics that could be introduced by reviewing the history of the topic before the writer gets down to the nitty gritty of his paper. It is important that the historical review be brief so that it does not take over the paper.