The background of the slide should allow the message to be easily distinguished. Most presentation packages have suggested backgrounds. Avoid white only, logos, fading tints, background patterns. Yellow type on a dark blue background is very effective. Make sure they are relevant to the message and are memory efficient.
Pictures can come from drawing packages, clip art, scanners or video cameras.
Insert blank slides where you want or anticipate student participation. Name slides with a system that easily allows you to identify them. This will enable you to quickly move between them if you need to change the order. Test a few initial slides on a friend, peer or student. Prepare slides well in advance.