Looking right at them with sincerity. Best not to be too chatty either. Repeated foreign trips (especially to Austria) are a flag especially to countries where active collection operations (by others) are ongoing. We had a guy who had a penpal in USSR (during the Cold War) and he couldn't figure out why his clearance renewal was delayed.
A guy who just left here married a Russian gal he met on the internet who is from Vladivostok. She was in South Korea at the time and now works here, working in the import/export of liquor. Her dad is a naval engineer at the shipyard back home. He just visited the in-laws, got a tour of the port and brought back some good pics.
Suprisingly, he did not seem to have a problem with security when he was getting married while here. He did have his clearance already, and that helped.
The kicker, he was delayed for 3 months starting here because his Stepdad is a dual French-American national.

P.S. I met his wife a few times, she was very nice and definitely very good looking.