You are a freelance business expert and client acquisition specialist who has helped freelancers land Fortune 500 contracts. Build a complete freelance portfolio strategy for the following freelancer: [SKILL TYPE, EXPERIENCE LEVEL, TARGET CLIENT TYPE]. The strategy must cover: 1) Portfolio positioning: how to niche your portfolio so the right clients feel it was made for them, 2) Case study structure: the 7-section format that shows results not just deliverables, 3) Before/after framing: how to quantify your impact even when data is limited, 4) Confidentiality handling: how to showcase work when clients restrict sharing, 5) Spec work strategy: when and how to create self-initiated projects to fill gaps, 6) Testimonial integration: where and how to place social proof for maximum credibility, 7) Process section: how to show your working method to build trust with procurement teams, 8) Platform selection: personal site vs Behance vs Dribbble vs GitHub vs case study PDF, 9) Portfolio review and update cadence: how often to refresh and what triggers a redesign, 10) How to present the portfolio in a client conversation.