Perfect BalanceThere are certain guidelines to follow in order to achieve total confidence without radiating an iota of arrogance. These should be followed constantly, both at work and play.
Care about your appearance
Most people significantly care about how others view them. Although it was stated above that this was a trait of arrogant fools, there's a certain minimum you have to contend with. Dress for the occasion. A well-tailored suit in a power meeting can do wonders for your confidence. Look the part but don't be a bragging pest about it.
Don't simply flash a "look-at-me, I-make-more-money-than-you-losers," grin; show an earnest smile. Co-workers will regard you as someone who is joyful and pleasant, a person with whom they'd like to be involved with.
Show interests in others
Take a moment to ask colleagues about their weekend. The goal is to show them you don't feel superior in any way. It will make them feel important and demonstrate that you care about them. But don't do it as a mere excuse to bless them with your own stories.
Stay on top of the events that are shaping the world. A large part of appearing confident is never hesitating. When a subject comes up, you need to be ready to jump in. It helps to have a multitude of interests and hobbies. At the same time, if you don't know what people are talking about, steer clear of the conversation.
Have an opinion
Similarly, make sure you have an opinion on key issues. Confident people aren't easily swept by peer pressure. If your belief isn't the most popular, have the courage of your convictions and stand your ground. Changing your mind at every occasion isn't the mark of a poised guy. Should you fall victim to it, you'll be branded an amateur. It can also come back to haunt you. Imagine two co-workers with whom you've shared two different opinions on the same topic. If they discover you're a shape-shifter, you'll be considered nothing short of opportunistic.
Expand your horizons
It may be important to build yourself a life outside of the office. With a well-rounded life, you'll feel much more confident and a lot more inclined to be assertive. Join a bowling league or the Optimists Club, anything that can garner some social interaction.
Be smooth with others
There are ways to deal with others to avoid being arrogant. For example, you might not agree with something your boss utters during a meeting. You may need to correct him, but do it without appearing brash. Don't make a point to mock him for his mistake, rather make it clear that you don't agree with him. Remark that you've made the same error before but have since come across new information that forced you to reevaluate your position. It's all in the way you present the situation.
Basically, what matters is that you can appear to be confident. Coolness is a virtual magnet for money, power and women. Everyone wants to hang around people who feel secure and positive. But if you can really be confident then the world will open itself up for you. Not only will you climb the proverbial corporate ladder faster, your relationship skills will be your greatest asset.