Every project is different, but my process stays roughly the same. Over six years of client work I've learned that the projects that go wrong usually skip one of these steps early on, and spend the rest of the time paying for it.
Step one is listening. I mean really listening — not waiting for the brief to finish so I can start sketching. I ask about the business problem first, the design problem second. What are they actually trying to achieve? What does success look like in six months? Who is the real audience? These questions take time, but they prevent a lot of expensive redesigns.
Steps two through five are research, sketching, prototyping, and handoff — in that order, without skipping. Research before sketching because assumptions are expensive. Sketching before prototyping because pixels commit you too early. Handoff done properly, with annotated Figma files and a walkthrough call, because a beautiful design that developers can't implement is just a mood board. The process isn't glamorous, but it works.