Congratulations, you’ve landed your first full-time job post graduation. Now it’s time to learn the corporate culture, make a good first impression and get  your career going.

"You should go in there to learn and serve your employer," says career coach Allan Fried of CareerIntervention.com. "Think about what value you can bring to them."

Millennials, who are now entering the job market, have been described by some employers as acting entitled, and career experts say this attitude can quickly derail your workplace successes early on and is one of the biggest mistakes they see in new hires.

“Having a bad attitude or sense of entitlement is the wrong way to go,” says Fried. “You are working for a salary, and are expected to do a good job—it doesn’t guarantee you anything else. Your success is up to you.”

So leave the entitled demeanor at the door on your first day, and avoid these career missteps:

Before You Get the Gig

Make sure you are listening and asking enough questions during the interview process to make sure the role fits your expectations, recommends Nicole Williams, career expert for LinkedIn. Younger workers often want to “seem smart” and talk more than they listen, she says.

“They don’t ask enough questions, or overcompensate. They should be asking others about their opinions, but they don’t because they don’t want to seem insecure.”

Ask questions about the actual job and the expectations and responsibilities, Fried adds, before you agree to take it. New grads may be seduced by the title or allure of working at a certain company without really having a clear picture of what their daily work life would be like, and quickly lead to unhappiness.

“The title may not be a reflection of what the job or the day is actually like,” he says.

Once in the Workplace

Pulling all-nighters and sleeping until noon are no longer an option in the real world, says Michael Crom, chief learning officer at Dale Carnegie, a leadership training firm.

“Never be late or come in tired or with low energy,” Crom says. “This may make you seen as a low-output individual. You want to be seen as a high-energy, high-positivity person. You want to come in early, stay late and work hard in between.”

And Crom says appearance is paramount—so break out the iron and be sure you look polished.

“You don’t need to have a big clothing budget, but companies want you to look neat and professional,” he says. “Your work space is the same way—you don’t want it to look the way your college desk looked with tons of papers and journals.”

And while making friends in the workplace is important, Fried says not to get wrapped up in workplace drama.

“We become the people we spend the most time with,” he says. “It’s toxic if you get in with the wrong crowd. Your career becomes doomed because it’s hard to resist hearing negative thoughts.”

Future Mistakes to Avoid

Don’t be afraid to take risks at the start of your career to move up the ladder, Williams says. Also, know that you are the one in charge of your career progression, and you have to make decisions for yourself.

“Don’t compare yourself to others or think of yourself in terms of others’ careers,” she says. “It’s your responsibility—it’s not up to your boss, HR, or anyone else to lead you. Have a sense of career goals and do what you need to do in order to advance your career.”

And if you do get into a company and realize it’s not for you, Fried says to realize you don’t have to stay there.

“A mistake is one thing, but if you are in the wrong job situation, it’s a bad decision to stay there for the next 10 years,” he says. “It doesn’t have to be your career.”

Follow Kate Rogers on Twitter at @KateRogersNews