It's natural after a job interview to want to feel like you aced it. But one of the contrarian truths of applying for any position, whether it be lumberjack, Baptist preacher, or assistant professor, is that you can overdo it.
You can exaggerate your qualifications, offer too much material, be too intricate in your answers, overreach in describing your research and teaching goals, and come off too strong in persona. The dimensions of the "overdo" are best studied—and guarded against—by looking at each component of the application process.
Cover letters. The head of a social-sciences department told me about one job candidate's letter that ran to nearly a dozen pages. The purpose of a cover letter is to formally notify the search committee that you are applying and to describe how you fit the post. Once you go beyond a page or two of self-description for an assistant-professor position, you are bordering on lexical obesity.
You want key items to stand out in your letter like skyscrapers on a plain. If, for example, you won a teaching award as a doctoral student, say so, and even add some context (the award only goes to one person a year and is voted on by both faculty members and undergraduates). Don't embellish by adding that "everybody praised me for winning the award." The search committee will hear such praise from the proper source, your references.
Teaching philosophy. No single item on the job-application checklist causes as much confusion and anxiety as the statement of teaching philosophy. I recall as painful and stilted my own first attempt to craft one. What could I say that was high-minded enough to qualify as a "philosophy"?
Once again, the best approach is to weigh the goals of the document. Show the hiring committee that you have thought about teaching, and would apply tactics to fit the pedagogical reality and aspirations of the target institution.
Principles and practice should not conflict in your statement. It is fine to write, "I believe every student deserves my personal attention," but someone on the search committee might reasonably ask, "In large lecture classes as well?"
I once read an excellent teaching statement written by a humanities applicant. She affirmed succinctly how she wanted to give each student the "best possible" classroom experience, but she placed the desire in the context of feasibility. She then explained how she prepared for new classes, how she organized the lesson plan, how she graded. She was communicating to the committee that (a) she understood that for its institution, a research university, teaching was one component of the expectations for her professional success and (b) she did not feel she was a perfect teacher but treated her "philosophy" as flexible. She cited some examples of failed assignments and described how she rectified them when she used them again. She came off as someone who took teaching seriously but not arrogantly or obsessively, which matched the culture of the department.
The CV. The format may vary by field and even by institution. Check out the online CV's of members of the search committee; their vitas are a good baseline to follow.
The actual content is guided by two rules of restraint. First, CV's are not a collection of Twitter tweets by a movie star. You do not need to document every event in your life. I have seen CV's stuffed with the topic of each class lecture, hobbies, (nonacademic) travels, even political philosophies. Interesting? Perhaps. Irrelevant? Absolutely. The search committee wants to know about your teaching history, conference presentations, publications, and so on. Don't bury such details in a forest of other material.
Second, the CV is a list of facts, not a propaganda tract. If you, as a doctoral student, designed a new course—an unusual achievement—just list it under a header of "New Courses Designed." Don't include endless description about it there. You can mention such details in passing in your cover letter and have your references talk about the course. Likewise, no need to say that you are well published; listing your publications is sufficient, as the search committee can, and will, count them.
Research presentation. I was a doctoral student when I first realized how a job candidate can overdo a research presentation. I watched an applicant who was poised and polished—indeed, overwhelmingly so, but not in a good way. His PowerPoint showed slide after slide of dense verbiage about a study that he described in Gatling-gun narration. He packed a six-hour lecture into 60 minutes, leaving about 30 seconds for questions. I felt vertigo from all the charts and bullet points flitting by. He was so eager to showcase his work that he forgot that a research presentation is not only about the research but also about your presentation of it—proving you have the ability to speak to groups of peers about your work clearly, concisely, and within time constraints. More is not necessarily better.
An overdone presentation will undermine your candidacy in another way if you are A.B.D. Search committees, professors, and the chair will wonder: Will she finish her dissertation in time to start the job? Be overlong, overcomplex, too wide-ranging, or overambitious in your talk and the impression will be, "Interesting, perhaps impressive, but no way will she finish by August!" Even if you are already an assistant professor, and on the market for a new position, you can undercut your chances with an overblown presentation. Blast the room with a massive research plan of stratosphere-reaching effort and the reaction might be, "I don't think he can pull it off and get tenure."
Teaching presentation. Approach this, too, by understanding its goals and audience. Your objective: to communicate that you are in command of the material, that you can establish and maintain a good rapport with students, and that you are an organized and competent instructor. Your audience will most likely include both students and faculty members.
Here too, you can overdo it. A friend told me about a job candidate who had a series of handouts for his teaching presentation that amounted to several hundred pages per student. Not surprisingly, his PowerPoint clocked in at a hefty 100 slides or more. In another case, I witnessed an assistant professor applying for a tenure-track job who was so eager to show off his brilliance that his high leaps of theory and dense statistical analysis flummoxed the undergraduates to whom he was speaking. He convinced the committee that he was indeed a smart fellow but a poor teacher.
Interviews. Your interview will include a lot of conversations. It is damaging to be overrehearsed—to answer every question like a politician at a debate who has memorized a stock answer and can't depart from his talking points. Reciting is not talking, and interviews are about showing you can listen as much as proving you can speak.
And don't talk too much. If you have a 15-minute conference interview, taking 14 minutes to answer the question "What is your dissertation about?" will not leave anyone awed—only dulled into daydreaming.
Overdoing it in your application materials or during an interview smacks of either arrogance or insecurity. Self-discipline and taking into account the wants and needs of the audience are traits everyone seeks in a prospective new colleague.