When writing your research statement (and cover letter), it is important to recognize that hiring committees will be swamped with applications. My main advice is to keep it short (2 pages should should be enough to explain your research). You can assume that the readers will be scanning the document and not reading every word, so make the important information stand out, such as key techniques or accomplishments. Cover letter should be 1 page max.
In addition, some applicants write their research statement as a short grant application, with clear motivation and specific aims. Depending on your field, that can be a great strategy. Your research statement will also be the outline for your chalk talk.