Exhaustively research your topic to ensure that you have enough information. Determine a navigation design. Rate the importance of adding imagery to a master slide. Assess consistency to ensure smooth transitions between slides. Apply adjustments if applicable.
Ensure credit is given to deserving sources.
Different audiences will be impressed by different imagery and content. Children will be impressed with relatively simple slides containing more graphics and less text. Conversely, adult audiences will probably require the reverse. If the show is only for your personal perusal, information that you might use later might prove helpful. Always present current and useful information.