Adobe provides a great breakdown of the fundamental rules behind visual brand identity and spells out what elements you should incorporate into a style guide for your business.  Get the article

Here's a handy, 4-step how-to on creating a brand style guide for your business from the Figma website.  Get the article

A solid article that spells out the fundamentals of media planning and buying. Key takeaway: effective planning requires a deep understanding of audience behavior and what each media platform can actually deliver.  Get the article

A bit simplistic, this article does a good job of explaining the difference between media planning and media buying.  Get the article