Hey, I'm Ivy, nice to meet you! I'm a professional GM, and love creating stories with people.
My best moments I ever create are always improv, so I like to spice up my pre-planned campaigns with things that are made up sometimes in the moment.
I tend not to run official modules, preferring my own homebrew content. The main reason for it, I find them to be constrictive to my creative freedom. Making them though? That's the epitome of fun.
I believe a story-arc shouldn't last more than 20 sessions, and each character you interact with should feel like more than just stats on a page.
My pet peeve is people who abide to the rules so strictly they actively ruin their player's fun. Rules lawyers are incredible, they understand things in a way that nobody else does. However if a group are trying to ask questions, and the book says a character gives no answers.... At least have it be in a fun way instead of just meta saying "They don't answer." Have their body language show their comfort or discomfort in the situation, have them try to change subjects etc!