Congratulations on graduating. Now go get health insurance

— -- For many college students, mortarboards aren't the only things up in the air on graduation day.

An estimated 1 million alumni dropped from their parents' health insurance coverage upon graduating this year. Replacing that insurance is a problem for former college students because they're often short on cash.

Graduates should aim for the most affordable plan: health insurance through employers, says Jon Gabel, senior fellow of the health policy and evaluation department at the National Opinion Research Center at the University of Chicago.

However, college graduates face a tough job market. More than 2.5 million recent college grads are unemployed, a National Association of Colleges and Employers report says. One of them is Samantha Whiteside, 24, a health and fitness major who graduated from Virginia Polytechnic University last year.

Her career outlook seemed promising at first. She found work at an outpatient rehabilitation center in March as a technician and wellness instructor for mentally ill seniors. She was told health insurance benefits would kick in after three months. Three days before her third month ended, she was laid off.

"I've never been in this situation before," she says. "I know everybody's been saying that the economy's bad … but I never thought it would happen to me."

She's working now as a part-time swimming instructor, and her mother, Marla Whiteside, enrolled her in an individual insurance plan with a $96 monthly premium. The coverage is minimal, and Marla Whiteside says she's worried because it only pays 70% of hospital treatment.

But while the plan isn't very comprehensive, it's better than nothing.

Graduates shouldn't join the ranks of the uninsured, warns Cheryl Fish-Parcham of Families USA, a health care advocacy organization.

Something as unpredictable as a car accident, or as simple as a few doctor's appointments, could plunge them deep into debt.

Also, if graduates wait too long to get health insurance, insurers may deny coverage, especially if they've had any major medical issues within the past five years, Fish-Parcham says. She recommends avoiding gaps in coverage lasting more than 63 days. Within that time period, if the graduate develops a serious health problem, federal law requires insurers to offer coverage. But after that, they can refuse you.