What I wish I knew when I started designing systems years ago

I started designing systems (also known as: architecture) 19 years ago. I’m not very smart, so I’ve made a LOT of mistakes on the way. Surprisingly it turned out these are quite common. I’d like to share a few things I’ve learned that would save me a lot of tears, had I known better back then.
I’ll talk about communication styles, how to design good modules, SLA, invariants and events, choreography vs orchestration, single point of truth vs data ownership, products vs projects.
This talk is for people starting with software architecture or anyone wondering about whether their next project should be REST microservices, Event Driven or a modular monolith.