1. Not offering any past managers as a reference. If your reference list is stocked with peers, employers are going to wonder why you don't want them talking to the people who supervised your work and whether you having something to hide—and many will call your past managers anyway.
2. Mentioning that lawyers are working out your split from your last job. No matter how warranted your lawsuit might be, most employers are spooked if they learn you're suing (or sued) a past employer. Fair or not, most want to avoid hiring anyone who they fear might be litigious.
3. Dismissing concerns about your experience. If an interviewer notes that you haven't had experience with a key part of the job, don't dismiss it with a breezy claim that you can learn anything. Savvy interviewers will be much more appreciative of a realistic view of the job's challenges and an honest conversation about how you'll approach them.
4. Being overly salesy in your pitch. Sales tactics are more likely to turn off your interviewer than to secure you the job. If you seem more interested in pushing your way into the job than making sure that the fit is right on both sides, you'll annoy your interviewer and often kill your chances.
5. Constantly checking in and asking for updates. It's easy to feel antsy when you're waiting to hear about a job, but following up repeatedly with an employer is more likely to annoy your contact than to get you the outcome you want. If an employer wants to interview you or make you an offer, they'll let you know; checking in weekly won't speed that up.
6. Lying, about anything. You might think it's minor to change your last job title or misrepresent your salary history, but to most employers, this will be an instant deal-breaker. Employers will assume that if you don't show integrity in the hiring process, you won't show it on the job either.
7. Explaining you've left more than one previous job because of the hours or workload. Interviewers understand that these are understandable reasons for leaving a job—once. But if it's a pattern, they'll start to wonder whether you're a prima donna who bristles at ever being asked to stay past 5:00 p.m. and who won't help out with extra work when needed.
8. Being overly cocky. If you appear to have an inflated sense of your own abilities and value, any sensible interviewer is going to worry about what you'll be like to work with. Will you take input and feedback, or insist you know best? Will you dominate meetings and alienate co-workers? Will you demand raises far beyond your value to the company?
9. Not having any questions about the job. If you don't have any questions about the job you're considering spending eight or more hours a day at, you'll come across as cavalier or disengaged. Interviewers want to hear that you're thinking critically about whether or not the role is the right fit, and that you understand what you'd be signing up for.
10. Sounding angry or bitter—about anything. Whether it's anger at a previous employer or bitterness over your trouble finding a job, there's no faster way to scare off an interviewer. Interviewers want to hire people who are upbeat and pleasant; if you sound like you have a sour outlook on life or work, they'll likely steer clear.
Alison Green writes the popular Ask a Manager blog, where she dispenses advice on career, job search, and management issues. She's also the co-author of Managing to Change the World: The Nonprofit Manager's Guide to Getting Results, and former chief of staff of a successful nonprofit organization, where she oversaw day-to-day staff management, hiring, firing, and employee development.