Step 4 - Content. Content includes text, font, charts, pictures, music, video, graphs, etc. Let's consider text first - although text is the most important part of any presentation, try to keep it in small doses - use direct speech, bullets, concise information, etc.
Create the text outlines in a word processor - make sure that the progression of slides has a flow to it.
Now, about slide backgrounds - how they reflect on projectors or monitors - about colour combinations and corporate identities.
Avoid fluorescent and very bright coloured backgrounds. Consider the type of graphs, charts...