Presentation software allows the creation of several versions of one presentation, and the possibility of including or excluding additional slides as needed. Check whether the necessary equipment to run the presentation will be available at the venue. If taking equipment overseas check also for electricity supply voltages, and need for adapter plugs. Most information conveyed in words should be in lower case type. The text should also have a reasonable 'body' and consistent thickness for visibility on differing screens.
Plain colours are usually best for readability.
Images and illustrations can be included where they convey an idea better than words. Most packages allow the inclusion of sound and video clips, and animations where necessary, but think whether they are appropriate. This may be of importance where the portability of the presentation is a consideration due to file sizes. Break material down in to visually digestible pieces. Always remove information and images which are no longer needed as soon as you have moved to another topic.