You have a job interview tomorrow. You've learned everything about the company, you're prepared for any questions they ask, and you even arrived a few minutes early. You couldn't be more ready.

But when you stop in the restroom for a last look in the mirror, your mind starts racing: "Am I dressed the way I should be for this interview?"

"In an interview situation, you're marketing yourself as a product, and so you want and need to have the best image possible," says Amy Glass, a trainer and coach at Brody Communications Ltd. of Jenkintown, Pennsylvania, and an expert on presentation skills, business etiquette, professional presence and interpersonal communication.

Presenting a professional image is more about doing your homework than spending money. So as you prepare for your interview, keep these wardrobe tips in mind.

It's OK to Ask What to Wear

In many traditional industries, like finance or accounting, business professional dress will be appropriate: A conservative suit, shirt and tie if you're a man, or a conservative suit if you're a woman, with -- perhaps -- personality shown through your shirt or jewelry, Glass says. In other industries such as advertising, public relations, graphic design and information technology, what to wear might be less clear. If that's the case, Glass says, ask about the company's general dress policies when you're first contacted about an interview.

"You can say to the person you speak with, 'I want to make sure I understand your company culture and dress appropriately,'" Glass notes. "It's not a bad thing at all. In fact, it shows respect."

If in doubt, err on the conservative side. "I've been overdressed at times, and that can be uncomfortable," Glass says. "But that's much better than being underdressed."

Shop Smart

You don't have to buy several suits for different interviews at the same company. In many instances, you can get by with one suit combined with what Glass calls a "capsule dressing" strategy -- varying what you wear with the suit each time.

"If I'm a young woman and I invest in a nice black pantsuit, I could use that one suit for interviews, but change the shirt, jewelry or scarf each time," says Glass.

You Don't Need to Spend a Fortune

Visit higher-end stores, like Nordstrom or Neiman Marcus, to look at interview clothes, Glass says. But when you're ready to buy something and money is tight, head for the outlet stores.

When considering your purchasing options look not so much at the specific price tags on various garments, but at the "cost per wearing," suggests Glass.

"Suppose you see a suit that's $150. If it's a trendy cut and it wasn't made of great fabric, you might be able to wear it once a month for two years. So your cost per wearing is fairly high. If you buy something for $300 instead, in a cut that will last longer -- not trendy but not old-fashioned either, and not screaming the year it was made -- your cost per wearing goes down dramatically. So don't look at the original price so much as how long the piece will be useful to you."

Don't Neglect Accessories

If you have leather shoes, Glass says, make sure they're shined. If you have suede shoes, make sure they're brushed. And if your shoes are five years old, have the soles redone at a shoemaker. If you have a leather briefcase and it's still in good shape, now's the time to use it. If you don't, a nice portfolio binder will do just fine.

Will all the effort and expense you put into your professional image for your interview make any difference? Absolutely, Glass says. In fact, it's essential.

"Your image matters because it shows your attentiveness to detail and gives recruiters an idea of how you'll represent their company to clients, both internally and externally," Glass concludes. "The visual message you send makes a big difference in how you're perceived and, ultimately, whether or not you get the job."