I was talking with the CEO of a tech company in New Jersey yesterday, and he told me something I think all job seekers should know — business attire is back.

When job candidates come to his door these days, they’re in trouble if they show up in jeans and sneakers. This guy isn’t a prude, mind you. He used to revel in the laid-back Silicon Valley type vibe that swept the nation in the past decade. But today, it’s all about being buttoned up and serious.

He gets so many job applicants for everyone job he has available these days, that people in casual interview attire look pretty bad among the suited-up job seekers.

Unfortunately, that may mean many of you have to go out and buy a suit and some nice collared shirts. Look in your closet. I bet there are a lot of outdated suits in there. Don’t wear them. There is nothing that screams “I’m incompetent” more than an 80s suit, or the suit you wore to your uncle’s wedding when you were 17.

I’m not saying you should head over to Brooks Brothers or anything. Head to the mall and find something that fits and looks sharp. Have you seen the sales lately? Or, visit your local Salvation Army. You would not believe the finds they have. The only thing I would suggest is dry cleaning the Salvation Army clothing before you wear them to an interview because most of the stuff you buy from their smells like your grandmother’s old hat box.

And folks, I’m not just talking about landing jobs at fancy corporations. Have you seen the lines at Target’s help-wanted desks lately? If you’re going up against someone dressed well and you show up in those fuzzy slippers everyone is wearing outside these days, you’re screwed.

OK, now that you have the right look, read my MSNBC.com column this week on acing the interview. I basically offer a range of interviewing techniques to think about. But the key is finding an approach that works for you.

I also got some great interview no nos last night from Alan Nierenberg, executive recruiter and author of Winning the Interview Game–Everything You Need to Know to Land the Job:

1. Do not do due diligence during the interview. You should research a company before you sit down with a hiring manager. It takes precious time away from the interviewer to evaluate you.

2. In response to the “Tell me about yourself” question, do not recite your chronological employment history. That information is on your resume sitting in front of the interviewer.

3. Do not “mirror” an interviewer’s body language in the hope of establishing rapport. It is easily recognized and it will result in a very short interview. There are more effective ways to establish rapport.

4. Job seekers at any age should not refer to accomplishments achieved 20 years ago. Keep accomplishments to the last 10 to 15 years.

5. Job seekers over 50 should not say they have 30 (or 25, or 20) years of experience. That statement triggers all the negative perceptions interviewers have about older workers.

6. When interviewing with a small company after working for a Fortune 500, do not describe projects where you had multi-million dollar budgets and a large staff.

7. Do not use humor more than once during an interview. You could be viewed as a jokester.

8. Do not go through an entire interview without discussing your skills for the position. The interviewer may have enjoyed talking about your mutual interest in traveling to France, but he/she will not be able to support your candidacy for the position.

9. Do not describe too many skills not listed in the position description. You may be viewed as too experienced or not having enough relevant experience.

10. Do not reiterate your sales pitch in a thank you note. If you did not do that during the interview, you will not be invited back.

What’s your take? Do you have a surefire interview technique? Or one that’s an interview killer? If you’re a hiring manager, tell us all what dumb things candidates have done lately so we can all steer clear of that behavior.