In my clients’ presentations that we make over (usually together), I see a lot of themes and slide masters that aren’t well prepared — sometimes not prepared at all. Setting up the theme and slide master, while it might seem time consuming, is actually a time saver because you avoid having to fiddle with each slide. And your slides will look better as well.
Here’s a video of a session from Power Pointers Quarter Hour that shows the process of how to create a theme in PowerPoint — similar to one that I often use. By watching it, you’ll learn the process and can then customize it for your own needs.
PowerPoint crashed during the session, but I was able to successfully complete the tutorial.