See this post by Bill Gray in reference to John E. Johnson's recent Bibliotheca Sacra article, “The Special Relevance of Ecclesiastes for Contemporary Culture” (Bibliotheca Sacra 169 : 159-71.I might add that Johnson's article also offers the following six "clues" to preaching Ecclesiastes (pp. 164-70).
1. Commit to work hard
2. Read in the context of wisdom literature
3. Welcome rather than avoid the conflicts and apparent contradictions
4. Find the exhortation
5. Move from theme to theme
6. Move to the gospel