Don't let love—or lust—make you reckless. There's no way to tell for sure if someone has a sexually transmitted disease, and often, the infections are symptomless. That means you should always use a condom. And remember, the more sexual partners you have, the greater your risk of infection, Roberts says. "There's an unfortunate myth that STDs only happen to bad people," he says. "You really can't make any accurate judgments about whether someone's going to have one of these diseases."
Bring a thermometer. Knowing whether you have a fever—and if so, how high—will help determine how sick you are and how soon you need to be seen by a doctor. In fact, that's the first question students are asked when they call the University of Wisconsin health center, Roberts says. "We have an on-call system for evenings and weekends, and part of what we have to figure out is whether students can wait until the next morning to come in or whether they need to head right to the emergency room," he says. "We ask if they have a fever, and they say 'maybe,' because they have no way of checking." Digital thermometers that give a quick readout are under $10.
Keep hand sanitizer handy. Germs are often spread through surfaces, like the keyboards in computer labs—you touch something that's infected, then put your hand in your mouth or eyes, and suddenly you're sick, too. Use an alcohol-based hand sanitizer after you compute, or after doing a lot of touching in a public place, like opening doors and pressing elevator buttons, Schaffner says. Alcohol is a drying agent, so a sanitizer with aloe vera may be easier on your hands.
Watch your feet. Drying between your toes after you shower—or swim—will help ward off athlete's foot, plantar warts, and other fungal conditions. Contrary to popular belief, flip-flops provide little more than a false sense of security, Roberts says. "For most people, it's more an aesthetic issue, with no proven health benefit," he says.