u/Feeling-Percentage89

I am the designated Keeper of my group, and having run my fair share of scenarios i'm looking to expand outside the official works into a custom/homegrown scenario, this is my first time doing so, not just in CoC, but in any ttrpg.

I'm a somewhat competent story writer, and the plot of the scenario is coming along nicely, but the gameplay resources side of things is all new to me...

Do any more experienced Keepers have advice that could help me? Common mistakes to avoid?, things i need to remember to include?

Any advice or resource recommendations would be greatly appreciated.