Sad path. Sad path. Sad path. So many times I see designs that are elegant only for happy path or assume nothing will ever go wrong. Plan and design for failure from the start.
Avoid transactionality across microservices... learned this one the hard way.
Borrow someone who hasn't been in the design sessions and explain it to them. Good gauge for if things are counter intuitive, over complex, or go against norms.
Plan MVP, MUP, and MAP iterations at least. Going all or nothing before seeing it operational is going to hurt you later. (Viable, usable, and adoptable for anyone not familiar with the latter 2)
TDD isn't just unit tests, know what payloads should generate what responses before you start so you can recognize gaps. Update your collection of tests as the project grows.
understand and incorporate client/ pm mvp, short term, and long term goals for the project but avoid over engineering flexibility that's not even in the roadmap
Thank you!! These are gems!