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Interns almost always offer cheap, reliable labor. But how far should you push your younger part-timers their first time on the job?

This year, 53% of U.S. companies with 100 or more employees will hire more interns than they did in 2012, according to Internships.com.

Thankfully, the talent is there; 65% of companies report receiving more applications than ever before.

Although interns can eventually turn into valuable full-time staffers (69% of companies made full-time offers to their interns last year), experts say there are some things your interns should never be asked to do, no matter how much you trust them or how desperate you are for a helping hand.

Here's a look at the best ways to manage interns -- for your benefit and theirs:

 1. Keep them away from sensitive information

Anything pertaining to employee records or sensitive customer information should always be off-limits to interns, says Michelle Benjamin, CEO and founder of TalentREADY, a talent management company.

"Depending on the industry, there can be several types of sensitive information," Benjamin says. When in doubt, leave anything private to full-time workers.

If interns will have access to confidential information -- even limited access -- it's essential to provide them with the proper nondisclosure agreements and training, says Amy Burton Loggins, an attorney at Atlanta law firm Taylor English Duma.

"You want to limit access to the most valuable or secret information," Loggins says, especially if it's proprietary or contains trade secrets.

2. Don't give them too many menial tasks

Most interns will be doing their fair share of printing, copying and ordering office supplies, but such work shouldn't be their main focus, Benjamin says. Instead, make sure that they have a defined project that they can complete during their internship.

"A good litmus test on how to treat your intern is asking yourself, 'If you were them, what would you feel about the task you're asking?'" says Liz Carey, a co-founder of leadership development firm Emerge. "If your answer is, 'I wouldn't feel too good about it,' then probably it is not a good idea to ask them to do that."

For example, you probably wouldn't feel right about saying, "I had them drive my car to pick up my dry cleaning," or "I had them get my Starbucks each morning," Carey says.

In general, avoid making "busy work" assignments, says Nathan Parcells, a co-founder and the chief marketing officer of InternMatch, an online platform that matches college students with employers.

"Your interns are with you to learn; giving them busy work wastes everybody's time," Parcells says. "Having them do filing and administrative duties will make your interns lose engagement, feel undervalued and unmotivated."

3. Avoid giving them unsupervised access to customers

Simply put, interns should not be placed in roles where they will have direct interaction with your customers, Benjamin says. Because of their inexperience and lack of knowledge about your company and its processes, they could say or do things that hurt your business.

"They could job-shadow or observe a customer service person, but should not be dealing directly with your customers," she says.