Probably the most important thing to possess in business is the ability to communicate ideas amply. This is true regardless of the position that you happen to fill in your job or company. You will need to communicate with people in every line of work, from customer relations to warehouse stocking. Therefore, it is extremely beneficial to hone these communication skills.
One of the most important elements of speech is clarity. Talking on and on without actually conveying the point does nobody any good when setting out to illustrate something. Though this is intuitively obvious, it is something that many people never seem to understand. A good way to manage this problem is to think about what you will be saying. Construct sentences in your head and try to make them as clear as possible. Since you are only engaging in casual conversation, there's no need to construct your sentences in too strict or formal. The key here is clarity, not grammatical perfection.
As with a great deal of other engagements, there is a lot to be said for interpersonal dialogue. This means that you need to engage in conversation with others as much as possible. When comparing somebody who is shy and quiet, somebody who is arrogant and rude, and somebody who is friendly and confident, who do you think is most likely to succeed in business, or any career for that matter?
As with anything, repeated practice will hone the skill to near perfection. This is especially true if, in addition to simply engaging in dialogue, you converse with other people about your communication skills. It ought not to be a person that you don't know too well, as you might bore them to death. Speak with a member of your family, or a close friend, when trying to pin down the individualities of your speech.