Former White House chief of staff Jack Lew testifies before the Senate Finance Committee on his nomination to be treasury secretary on February 13, 2013 in the Dirksen Senate Office Building on Capitol Hill in Washington, D.C. - 

Jack Lew was sworn in as new Treasury Secretary today. He probably had a rough first day on the job. There's a lot on his plate -- with those big federal spending cuts looming tomorrow. Which got us to thinking: How can you avoid pitfalls your first day on a new job? We asked the experts -- people with first-day horror stories you won’t believe.

We came across Marvin Address at a food truck in downtown Washington. He owns an insurance company now, but his first job  was in the Air Force working as an air traffic controller. He was nervous on his first day -- so jittery, he lined up two planes to take off. Facing each other.

“And I got a call in the tower," he says. "And the pilot said, 'Tower, am I looking at another airplane that’s coming my way?'”

Luckily, Address was able to re-route the planes and no one was hurt. But he learned an important lesson that day: Keep your eyes open -- literally.

Another lesson might be "know thyself." Victoria Hernandez got a job at a chocolate bar factory a few years ago -- not knowing she was pregnant and suffering from morning sickness. She says, “I guess the aroma got to me so bad."

Yeah, you know what happened next.

“I threw up all over the conveyor belt," she says. "And all over the chocolate bars and everything. They had to shut down the whole left side of the building because of me."

Kathy Caprino is a career coach. She says if you screw up, or throw up, the first day on the job, admit your mistake. If it’s not too serious, try to laugh it off. But she says it’s best to try to prevent first-day slip ups in the first place.

“Get hip to your own trip,"she says. "What are the things that could trip you up? Look at those and protect against those."

And here’s some advice that could help our new Treasury Secretary. If you’re a new manager, you embody the hopes and fears of your workplace. Or, in Jack Lew’s case, your country. Just do your best. Don’t take anything personally. And have a thick skin.

We asked our Facebook fans for their own first day horror stories. Here's what you told us.