Overconfidence is a problem in business. It's particularly bad when you marry it with ignorance.

But real and reasonable confidence? It's alluring. So is authority. Getting people to invest trust and the power of decision in you is an important step in making sales, closing deals, and managing teams. You don't have to leave confidence or authority to chance. Here are seven things that studies have shown can fan your confidence and have people see you as a figure of authority.

Use the voice

Researchers from San Diego State University and Columbia University found in a recently published study that how people speak conveys hierarchical rank--status, if you will. Making your voice sound right can help in any kind of negotiation. Right means speaking in a more monotonic tone and higher pitch with more variability in loudness.

Spread out

The proper body language can reduce stress and improve confidence. Before a meeting or negotiation, find a private place and stand for a couple of minutes with your arms and legs stretched out, taking up as much room as possible. Doing so isn't just a mind game: testosterone, a hormone associated with confidence, increases while the levels of stress hormone cortisol drop.

Sit up

Posture is actually as important as your mom used to say. Sitting straight up boosts confidence according to an Ohio State study.

Turn up the bass

Background music affects your mood. You can make it work for you, according to researchers at the Kellogg School of Management at Northwestern University. They found that bass-heavy music is empowering, so people listening to it felt more confident. Yup, there's a reason you might want to turn on booming, thumping tunes when trying to psych yourself up.

Dress right

Another study out of the Kellogg School says that what you wear is important to how you feel and work. Clothing has symbolic meaning. Wear what you think of as a white lab coat and you become more attentive. The study showed that the lab coat wearers made half as many mistakes as a control group. Say the same coat is actually an artist's smock and the advantage disappears. If you associate a suit and tie with power, wearing them will have an impact on how you feel. But if you think "suits" are phonies, then wearing one is exactly the wrong thing to do. There is even science behind what could work best, suggesting that dark colors and straight lines convey authority, for example.

Learn (or relearn) a skill

Researchers in the U.K. found that adult learning can benefit confidence and self-esteem. Studying art, computers, math, or a language can give you a boost. Another benefit: improved health.

Get on a winning streak

Neurobiology recognizes something called the "winner effect." In short, when you win a competition, you're more likely to win the next one because you go into it with higher testosterone levels. By winning, you create a positive feedback loop in which you continue to be more prepared and stand a better chance of winning. So make sure you have plenty of opportunity to excel.