my experience based on academic presentations rather than business so may not all apply, but my general rules:
Use numbers 1) rather than bullet points as it's easier to refer to whilst talking
Max 5 points no more than 7/8 words each slide.
Use images/tables/graphs where appropriate. Don't just throw in a table for the sake of it and make sure you talk about it if it's there.
Practise. Practise. Practise. If they've given you 15 minutes practise it through to make sure it's 15 minutes. Don't settle for 'well 16 is close enough'. If there's a particular part you always struggle on slow down when you get there
I like to set an image/photograph as the background and set the transparency to 50-75%. Maybe less appropriate here though
When you really want to push home a point, as someone said earlier, black text on white background can be very effective.
Finally once you've plugged in the USB, drag your slides to the desktop and run it from there. USBs can sometimes malfunction at the worst time...