The anonymity of Internet dating has obvious hazards. If you're looking for love, your contact may be looking for just a quickie. Establish upfront what you are really searching for. Talk on the phone first, then arrange a brief meeting in a public place—for coffee, lunch or maybe a drink.

Dating advice: Take your cell phone with you. Let someone know where you're going, who you'll be meeting. Arrange to call your friend at a specific time. Park in a well-lit place. When the first date ends, don't let them walk you to your car. You don't want them to know your license plate.

Schwartz is relationship counselor for Perfectmatch.com. "I've used all the dating services … I think online dating is great, absolutely the best thing of the 21st century. I've met some very special people."

Beyond people shaving a few years off their age, "I've never met anybody online who lied," she tells WebMD. "As long as they haven't said they're 40 and they're really 60. But I've never met anyone totally different than they present themselves."

But if someone lies about his or her weight—lies to the extreme, that is—that's what people really get upset about. "It's very unwise for women to substantially stretch their weight. If you're a size 14 or more, it's not fair. Just say, 'I'm heavy but still think I look great. You be the judge,'" Schwartz says.