The following is the 13th installment from Heartland Immigration's e-book, How to Get a Visa for the United States.
5. Be pleasant - a smile will get you far
Understand that consular officers go through many interviews during a given day - over 100 in some embassies and consulates - and have to deal with a lot of lying. Consular work can be a real grind. This makes consular officers really, really appreciate when an applicant is particularly pleasant. Being pleasant - smiling, being accommodating and upbeat (without going overboard) - can really help to put the consular officer in a good mood; this can only work to your benefit. In border-line cases, where the consular officer isn't quite sure which way to go (as in, whether to give you a visa or deny you, based on your qualifications for the visa), as a matter of human psychology it's much better to have them inclined to like you personally than to see as just another applicant who's standing between them and being done for the day. So be nice. Act like you're glad to be there. Smile.
6. Be up front and honest
With visa interviews, the adage that honesty is the best policy holds true. You'll notice in filling out the application that there are some questions that basically boil down to "have you ever done anything bad?" Be honest. The fact that you've got something less than honorable in your past doesn't necessarily mean that you'll be denied a visa. While answering "yes" to a few of these questions is an automatic disqualifier (like the one about belonging to a terrorist group), this isn't the case for most of them. For minor things, like a run-in with the law for something quite innocent, there likely won't be a problem. But lying about it can possibly make you permanently ineligible for a visa. How, you might ask, could they possibly know about something from my past? It's not a given that they will, but there's a chance. Authorities in many countries share information with the U.S., and any legal issues you've had in the U.S. on prior trips are likely to be brought to the consular officer's attention. Additionally, the consular officer has been trained to spot lies. You may get caught, you may not - better, in this former consular officer's opinion, to be truthful and explain the circumstances than to risk a permanent ban from the U.S.
You'll have a chance to explain what happened and why. Even if something in your past makes you technically ineligible for a visa under U.S. immigration law, waivers exist for most things. To process an application for a waiver, the consular officer will send the information for your case over to the Department of Homeland Security (DHS), including notes about the interview and a recommendation as to whether DHS (who has the ultimate decision) should grant the waiver. It's probable that being upfront and honest about the incident(s) will make the consular officer more likely to recommend that a waiver be granted and to portray the incident and you in a favorable light. You definitely want them on your side if a waiver is needed.