One of the most common mistakes that presenters make is failing to modify written work for spoken presentations. Obviously we don't write and speak in the same way – and the language used in your presentation should reflect these differences.

Keep It Simple
Remember that your audience doesn't have the luxury of rereading a particular sentence or paragraph. If they don't grasp your point immediately, you've lost them. Don't use your presentation to showcase your extensive vocabulary (or to utilize a great thesaurus). Instead, use short, familiar words. "It's rare to see a purchase like this in the garment industry" is much clearer than "A procurement of this type is unprecedented in the garment industry."

Keep It Short
In the same vein, use short sentences. For example, "Please let me know if there's any further information you need" versus "Please feel free to contact me by phone or e-mail if you have any questions or require any further assistance in the near future." Not only are short sentences clearer to the audience, they're easier for you to deliver without pausing mid-sentence.

Make It Clear
Avoid vagueness at all costs. Your audience will start tuning out, and once their interest wanes, it's difficult to get it back. For example, "Profitability is estimated to decline in the next fiscal year" is nowhere near as memorable as "Sales are estimated to fall by 33% in the next 12 months. That's a $2.3 million loss."

Make It Visual
Use visual references that your audience can relate to. "Our upcoming ad campaign will feature three 24' x 30' billboards" will be instantly forgotten. While "Our upcoming ad campaign will feature three 24' x 30' billboards – each billboard being the size of a double-decker bus" provides a visual reference that will reinforce your message.

Make It Personal
Use personal rather than impersonal language. "I'm sure you all realize the implications of this policy" will resonate more with your audience than, "This group is bound to realize the implications of this policy."

Make It Relevant
Tailor your presentation to your audience. If you're speaking to a group of colleagues, use colloquialisms and jargon where appropriate. If you're pitching an account to a new client, use formal language. The key to effective communication is using language that will help you relate to your audience.