There can be much value in the ability to take a back seat from time to time.  Demure, modest individuals can possess many wonderful qualities, like the ability to listen, reflect, and offer plentiful insight. However, there is a time and place to reserve timid moments and submissive behavior, and that time is NOT when you are attempting to make a big move in your career.  There are plenty of ways both introverts and extroverts can live in corporate harmony (as demonstrated in some of our past blog posts); however, when trying to really boost your professional momentum and take your career to the next level, it is often times necessary to establish yourself as an authority within your office.
This means it is time to become visibly confident, so coworkers and superiors see you as someone assured in their abilities and knowledge, and not afraid to take action and self-start; these are qualities necessary for a business to continue to evolve and develop, and qualities many people look for in their company’s leaders.  This does not mean we all must become brash and boisterous when looking to get noticed for a raise or promotion.  Instead, there are minor adjustments you can make to even just your appearance, body language, or communication to convey authority and command over your career, and garner respect from your colleagues.  
You can check out some of these tips below from a Yahoo Shine article on appearing more authoritative. Once you show that you are confident in yourself, your superiors will be more likely to put their confidence in you to take on more responsibility or bigger roles.

Stand up while you’re on the phone.

It may sound silly, but getting up out of your chair while you’re on an important call—whether it’s to your insurance provider or a potential employer––can help make your voice sound more authoritative. “Your voice is closely linked to your body and physicality,” says Susan Berkley, author of Speak to Influence and president of The Great Voice Company. “When you’re standing up and gesticulating, you’re going to have more energy than if you’re sitting down, relaxing in your chair. You’re pumping yourself up physically and it’s going to come through in your voice.” Plus, she notes that when we stand up straight, we breathe more fully, enhancing the power of our voice.
Avoid turning statements into questions.

“It drives me nuts when I’m in a coffee shop and a woman places an order that sounds like a question: ‘I’d like a latte?’” says Ginny Clarke, career coach and author of Career Mapping. “Do you or don’t you want a latte?” By allowing the tone of your voice to rise at the end of a sentence, you’re subconsciously undermining your own authority by treating your statements as questions. “Tell someone what you’re thinking,” Clarke stresses, “don’t ask them.” According to her, we often do this in mundane circumstances, like when ordering food or responding to simple questions. To overcome this habit, she recommends keeping the three “Ds” in mind: Be decisive, definitive and deliberate. “And never answer a question with a question,” she adds. “If you need clarification, lead with a statement like: ‘Let me make sure I understand you. Are you asking if…’”
Dress the part.

Dressing for success doesn’t necessarily mean donning a suit. Instead, make a note of what everyone else is wearing, and emulate their style in a put-together way. If the dress code at work is slacks and a button-down shirt, invest in a few sharp-looking separates that will ensure you fit in with the office culture. “Dressing conservatively for the sake of getting respect will make you seem out of touch with what the organization needs, and that can automatically undermine your authority,” says Dawn Chandler, a career management and HR professor at the California Polytechnic State University.

Make eye contact.

Whether you’re giving a presentation to a roomful of people or negotiating a better deal on a car repair, making eye contact is key. As Antoinette Kuritz, a publicist in San Diego, notes, when you’re so focused on what you’re saying or doing it can be easy to converse with people without actually looking at them. “Making eye contact infers that what you have to say is important and that the person to whom you are saying it is important, too,” says Clarke. “People will remember you when they sense that you’ve really seen and paid attention to them.”

Pause before hitting Send.

Before firing off a hasty response to an email from your boss, wait a few extra minutes to see what other information you can gather. Constant accessibility has become the norm these days, but a rapid reply simply acknowledging that you got her message, without a real thoughtful answer to her question, isn’t the way to command respect. “Instead of sending five emails that don’t say much, stop and gather good information so that you can provide her with a more considered answer.” Even better: When appropriate, head over to her office to discuss her inquiry, or ask your own questions. By showing up in person you’ll appear more confident than if you quietly send out a stream of emails.
Make yourself visible at meetings.

When it comes to commanding authority, “having height helps,” says Clarke. “You want to stand as often as possible.” This means rising when someone comes to chat with you at your desk or standing, when appropriate, during meetings. Being so visible, you may also be called to question or comment first, which can work in your favor.

Don’t lead with a disclaimer.

According to Clarke, women tend to pepper their ideas with disclaimers and apologies, like “I don’t know if this will work, but…” or “This might not be what you were thinking of, but…” Instead of giving your audience a reason to discount what may be an excellent idea, present it without any judgment at all and let them decide what they think. You’ll be surprised at how much people will trust you if you trust yourself. In situations that require a disclaimer, Clarke recommends making it after you’ve asserted your facts or opinion; for example: “I don’t think we should move forward with this project, unless of course I don’t have the latest data that would suggest otherwise.”
Manage your boss’s expectations.

Think that promising to tackle that giant pile of expense reports by 5 p.m., despite having no experience with accounting, will endear you to your boss? Offering to take on work that is outside your area of expertise won’t impress anyone—especially when you turn in a less-than-stellar final product. On the other hand, avoiding projects like the plague won’t impress your superiors either, since being a team player is essential for career development. If you’re asked to do (or want to volunteer for) something that you know you can’t handle alone, be honest about your limitations, advises Clarke. “Say something like, ‘I’m always up for learning, but this project might take me a little bit longer and I may need a few extra resources.’ People will respect you more for being honest rather then taking the assignment, turning it in late and flubbing it.” Plus, you’ll be able to manage your team’s expectations while still giving yourself a fair shot to complete the work.