In addition to wearing a wedding ring, the guide, "Her Own Way -- A Woman's Safe-travel Guide" suggests single female travelers go a step further.
"Also carry a photo of your husband (or an imaginary one), which you can show to persistent suitors," the guide says. "Being seen as married will lower your profile and stave off uninvited advances."
The advisory doesn't name specific countries or cultures, but suggests women do their homework before they travel alone to avoid attention.
Among the suggestions is to avoid eye contact.
"In some cultures, meeting a man's gaze may suggest that you want his company," the guide says. "A simple solution is to wear dark glasses in public places."
The department also cautions blondes about consequences of their hair color.
"If you're fair-haired in a country where most women are dark-haired, you may attract unwanted attention, the guide says. "Consider wearing a headscarf or hat."