My parents didn’t get off to a great start.

He was a technician working in a shop that sold and repaired radios and televisions, and she came in to buy a small radio for her boyfriend. Because the boyfriend was in the military, she had to give his full name for the shipping label. Part of the young man’s given name was … Elsie. My dad had an aunt named Elsie. He was very amused. Mom, not so much.

They met again when my dad came into the fountain where my mom worked a second job as a soda jerk. The first meeting had been somewhat out of character for both of them. Typically, he was more reserved and she had a better sense of humor. Things began to go more smoothly after their second encounter … for everyone but Elsie.

Even if you make a horrible first impression, you might get the opportunity for a do-over—but not if you blow it during a job interview, sales pitch, or some other once-in-a-lifetime moment. Here are a few tips to help you leave a positive impression the first time:

• Eyes have it.  Have you ever noticed that in some casual restaurants—such as America’s Outback Steakhouse franchises—waiters often squat beside the table to take the order? It’s not because they find the position more comfortable. They want to be able to look you in the eye as you’re interacting. It’s a proven way of getting a higher tip. Especially now, when so many people feel they’re playing second or third to a cell phone or handheld computer game, giving someone your undivided attention—signaled through eye contact—is a sure way to make positive points. Just be careful that you don’t cross the line from attentive to creepy. Look at the other person in an interested way, but don’t go into a wide-eyed fixed stare.

• Show of hands.  According to a recent survey by researchers at the University of Manchester in northern England, nearly 20 percent of us balk at having to shake hands. Gee, that’s too bad—since handshakes have been around for thousands of years, and it’s estimated we’ll perform about 15,000 of them in an average lifespan. And male or female, there’s a formula for doing it right, says Geoffrey Beattie, the university’s head of psychological sciences. After evaluating 12 key measures, he offers this advice:

Making sure your palm is cool and dry, take your right hand and grasp the other’s right hand in a complete, firm squeeze—not too strong. Pump approximately three times with a medium level of vigor for no longer than two or three seconds. Maintain eye contact and a natural smile throughout, and offer an appropriate verbal greeting.

• A winning smile.  This may seem to be a no-brainer, but the challenge isn’t to come up with an automatic smile, but one that appears warm and genuine. Sharon Sayler, author of What Your Body Says (And How to Master the Message), says that allowing a slow smile to unfold will come across as more sincere than flashing a quick, toothy smile—you know, the politician’s trademark. And if you’re genuinely pleased to see the other person, that sincere smile should happen naturally.