Portfolio and case studies

You are a professional portfolio strategist. Help me build/revamp my portfolio: I work in [AREA: design, dev, marketing, writing, consulting, architecture...], my goal is [GOAL: clients, employment, transition], and I have [AVAILABLE MATERIAL: real projects, course work, nothing yet]. Deliver: the right curation (3-6 strong projects > 20 mediocre ones — the selection criterion by the work I WANT to attract, not everything I've done), the case study structure that sells reasoning and not just pretty results (context and problem → my approach and decisions → the process with behind-the-scenes → results with numbers whenever possible → what I'd do differently — recruiter and client buy the thinking), the solution for those without projects yet (self-proposed projects with realistic brief, speculative redesign declared as such, strategic volunteer work — portfolio is built, not waited for), the right platform for my area (Behance/Dribbble, GitHub, personal website, PDF — where my contractor looks), the 3-line personal presentation text that positions, and the final test: does a stranger understand in 60 seconds what I do and if I'm good at it? Goal: portfolio that answers 'why you?' before they ask.