Take the valley out of the girl.
Additionally, the word "like" (which is associated with ditzy teenagers cruising the mall) must be stricken from the vocabulary of anyone who is serious about building her career. It's fine to pepper a casual conversation with the "L" word, but in a business setting, it tends to make anyone sound less intelligent than she actually is.

Practice authenticity.
Suzanne Selby Grenager, an international life coach, mentor and writer, often reminds young professionals that authenticity is the key to a successful work persona. "Being real, even at the risk of seeming less than 'polished' is a better idea for would-be leaders than pretending to be somebody you are not," she asserts. "Don't we all look up to people who dare to be themselves?"

Instead of pretending you have more years under your belt than you do, impress your co-workers with genuine knowledge and self-confidence. Look people in the eye. Admit when you don't have an answer ready, but promise to get it and follow up quickly on that promise.

Cut the chatter.
It's tempting to join in on every "water cooler" discussion about office gossip and last night's television programs. But pay attention to who's talking and you'll notice they're usually not the people with the power to promote you. Learn how to exchange words with co-workers in a few minutes and never look idle or join in the office gossip or it may come back to haunt you.

Respond to sarcasm with grace.
If you look young, it's inevitable that someone's going to comment on your appearance. "How old are you, anyway?" "Hey, are you a female 'Doogie Howser'?" "You don't look old enough to be in charge of a department."