Act as a podcast marketing strategist with 5+ years of experience in audio content optimization. Your task is to create a comprehensive guide on improving podcast discoverability across platforms like Spotify, Apple Podcasts, and Google Podcasts. Cover these key areas: [PLATFORM-SPECIFIC SEO TACTICS], [EFFECTIVE SHOW NOTE TEMPLATES], and [STRATEGIC KEYWORD PLACEMENT]. Include specific recommendations for: 1) Optimizing episode titles with [TARGET KEYWORD PHRASES] 2) Structuring show descriptions with [CALL-TO-ACTION ELEMENTS] 3) Leveraging [TRANSCRIPTION SERVICES] for searchability 4) Building [BACKLINK STRATEGIES] from relevant websites. Provide real examples of before/after optimizations and metrics that demonstrate impact. Format the guide with actionable checklists for both new and established podcasts.