I have been on a small quest to read as MANY books about being a better DM as I can. I've read a fair chunk of the Kobold Guides, How to Write Adventure Modules that Don't Suck, and a fair few others. I've run I think close to 50 games in the last year, my first year of DnD at all.
Out of all of that, @slyflourish's Forge of Foes has had the biggest impact on my players. I've always focused on the narrative and not been great at combat. The tables have turned!
Things will still be kept fair, fun, and balanced, BUT... before this, my players had successfully slain one of my BBEG's before it ever got a chance to even attack.
I.. really hammed up my responses that night, "NOOOO, HE NEVER HAD A CHANCE!"
They're not gonna slay another BBEG before it even gets to roar at them.