Beauty is in the EYE of the Designer.
This, does not mean that there are not specific trends and guidelines that assure that your design work is loved by many.
No 1. VISUALISE
Thou shall not flood with excessive text.
Whilst it is nice to explain in copy, it is not appealing to write whole bibles on your graphics. Instead, engage the senses and tell a story with your images and graphics and keep text to the bare minimum.
No 2. USE DIFFERENT MEDIA
Thou shall experiment with videos, images, animations and the lot.
Experiment and see what triggers the most engagement amongst your audience.