Secret #1 - No Jargon
The most important secret is: do not use jargon.
It's so easy to use your indus-try's or your company's jargon during a presentation. Whether you are speaking to work colleges, people in your industry or your clients, stay away from jargon.
Don't make the assumption that your audience has the same understanding of your jargon that you do.
Your message will be lost if your audience can't under-stand what you are saying.
Be aware that there are two different instances of jargon; in the first, it comes across as a completely different language; in the second there is a potential for a different level of understanding than yours.
You will also want to watch your use of idioms and colloquialisms.
An idiom is a word or group of words established by usage as having a meaning not deducible from those of the individual words. A common example is "raining like cats and dogs". While the use of idioms can make your language richer and more colorful, they could be misunderstood.
A colloquialism is a word or phrase that is not formal or literary, typically one used in ordinary or familiar conversation. Common examples are: wanta for want to, gonna for going to, buzz off for go away. When used during a presentation, your audience can get the feeling that you are sloppy or uneducated.