Creating engaging slides is crucial for the learning experience. Since you can't field questions from students when creating online content, you need to ensure that your slides clearly and effectively demonstrate the concepts you are teaching in your lessons. While this can be difficult, especially if you more familiar with teaching in front of an audience, it is possible. The following provides some tips to help you out.
Good ideas
Use images. Whether they are pictures, plots, or diagrams, having images in your videos helps students learn, and makes the course adverts more photogenic, which helps to increase the number of students starting your course.
More is not better - or worse. Too few slides can be boring; too many can be overwhelming. A reasonable heuristic is to have "one slide per idea." That is, anytime you introduce a new idea in words, you also change what is onscreen.
Use dual coding. When words and visuals match ("dual coding"), it can increase learning relative to a single communication channel.
Include a summary slide. It can be hard to remember everything that is spoken in a video. Having a summary slide can help students to be aware of what they just learned.
Common problems and their solutions
Too much information. Videos need to be understandable in real-time, so err on the side of simplifying things and omitting things. Try to not include full sentences on your slides as well, but rather just short bullet points with your script giving more information.
Speech and slide mismatches. While complementary speech and slides provide a boost to learning (see "Use dual coding" point), having mismatched speech and slides detracts from learning since the student has to decipher which of the two media they should pay attention to. Double check your presentation to ensure that information presented on the slides is also in the script and vice versa.
Too much talk, not enough action. Spending a lot of time talking on a slide while nothing happens on the screen, can be a bit boring and you run the risk of losing your student's attention. Make sure there is something dynamic happening, an animation or a slide transition, every 30 seconds.
Don't use memes. These often get dated incredibly quickly and detract from the premium feel of the content. If you wouldn't have gotten the reference a year ago, don't use it.
Examples
From What is code profiling in "Writing Efficient R Code." As well as having the instructor dressed up to match the dataset being discussed, this also makes good use of images and screenshots.
From Embrace, Extend, Override in "Object-Oriented Programming in R:S3 & R6." This makes use of a physical prop to demonstrate the concept. It also includes a summary slide at the end.