Utilize themes that are built into Powerpoint and Google Slides in order to give you presentation a professional look. Using a different photo for each background will give you background a confusing disorganized look. See the screenshots to see where to find the themes built into Powerpoint and Google Slides. You can also find themes online at websites such as Slide Carnival. 

Instead of making pictures your background, diversify the look of each slide by using different layouts. Layouts will make your slides look nice and professional. See the screenshots to see where to find layouts in Powerpoint and Google Slides

It is important to use pictures in an effective way when you are creating a presentation. Making pictures as your background can be very messy! Instead, use the layouts to put a picture next to your text. Please remember to always "label for reuse" in Google Images and to cite your images! See the pictures section of the Noodle Tools for a refresher on how to cite photos. 

Make sure that whatever themes or backgrounds you use it is easy to read. You do not want to put time and effort into a presentation that your audience cannot read!

To much Text!

Make sure that your slides are not overloaded! Each slide should have just enough text, but not to much!