Hundreds of advertising job seekers make avoidable mistakes when approaching top agencies -- although some are more obvious than others.

“I once had a candidate show up on the front steps of our building and sing his resume to the tune of 'Oh Susanna' while playing the banjo," says James Hering, executive vice president and director of integrated marketing at TM Advertising, a unit of McCann-Erickson that works on behalf of American Airlines, among other clients.

"At all costs, avoid delivering your resume or credentials via singing telegram, mime or circus clown," Hering advises. "Clown equals no interview for sure."

Hering is not the only ad exec with unusual stories to tell. "We receive direct-mail pieces in which the person is trying to be clever by sending some gimmick or pun-oriented item," says Mary King, creative talent director at Ogilvy. "I can't tell you how many ‘things' I've received in an effort to be remembered."

To score an enviable copywriter, art director or account management position with a firm that's a brand name in its own right, steer clear of these five faux pas, as identified by top agency recruiters and human resources managers nationwide.

Covering Too Much in the Cover Letter

Cover letters should include a clear value proposition as to what you can bring to the agency, your objectives and how your objectives relate to your experience," says Laura Wallace, a recruiter at Saatchi & Saatchi Los Angeles, which handles Toyota's ad account.

Deanna Grams, HR manager for Publicis & Hal Riney, the agency of record for Hilton Hotels & Resorts, looks for brevity. "I think a lot of people give way too much detail," she says. "I want to learn in two paragraphs or less why you want to work for us and why we should hire you over any other candidate."

Of course, cover letters should be well-written and proofed. "A lot of times, I see cover letters addressed to the wrong company," Wallace says. Oops.

Running on at the Resume

“We see a ton of resumes," says Grams. "A major pet peeve is when people don't organize their work history in an easy-to-read manner. Tell me what you do or what you've done in two pages or less.

And save head shots for your grandma, Grams advises. "We're looking strictly at talent and experience," she says.

King's agency represents Northwest Airlines, among other heavy-hitting brands. "We find PDF samples of work or a Web site more informative than a resume," she says. "It [is] much more effective to demonstrate your skills by creating something that reveals who you are in an imaginative, conceptual way."

Not Properly Preparing for Interviews

Interviews require a certain amount of preparation. "Under-preparation happens all the time," Grams says. "Candidates come late or without a resume. Or they don't know a thing about the position or the company itself."

Check out an agency's Web site, visit trade magazines online, or search the Web for recent firm news. Figure out how and why you'd fit a prospective employer.

In short, err on the side of over-preparedness, if such a side exists. "I'm always impressed when candidates know more about the company than I do," Wallace says.

strong style="font-weight: bold;">Playing It Too Straight

Don't unnecessarily restrain sincere emotion. "We have a really genuine and enthusiastic team at Riney and are looking for more of the same," Grams says. "We love people with personality and an opinion, so candidates who don't seem interested or excited about the opportunity don't generally make it to the next round."

Wallace says an uptight physical demeanor -- even if it's intended to convey consummate professionalism or the maturity of your experience -- can be a turnoff. Smile, ask questions and treat all agency staff you encounter on your visit to the office equally. "We always ask the assistants that help facilitate interviews what they think and how candidates treated them," she says. "In some cases, it's helped us make hiring decisions."

Making Too Much of Yourself

Since it's a sister discipline to marketing, those in advertising are familiar with promotions and the energy around an active way to pitch a product. Job candidates will sell themselves in an interview, but in getting a meeting at an ad agency, you'll be selling yourself to the savviest of sellers. Keep it simple. "There are candidates who talk too much -- way above and beyond the questions asked," Wallace says.

So how do you know you've gone too far? "When self-promotion is completely self-congratulating -- when [candidates are] obviously more interested in hearing themselves talk than the opportunity," Grams says.