Start with Scenarios
I’ve been finding it incredibly useful to write narrative style user scenarios. Like a lot of the stuff I write, *I try* to keep them short and concise. Exactly how a user’s experience should be: quick and intuitive.
Scenarios answer the who, how, and why. Those are three really important things to know and solidify in the process. So much so that if you have an idea, start with scenarios! It’ll flush out who your users are, how they should interact with your product/service, and fundamentally why are they doing it.
I think the why is the most important — we need to always keep in mind what their goal is and what they want to get out of the interaction (so help get them there easier!).
Having those things flushed out should save a lot of time working on the features that aren’t that important.