Lean marketing focuses on testing different marketing channels like PR, SEO, social media, email, and direct sales to determine which channels are most effective. A company should 1) develop new marketing channels and campaigns, 2) measure the traffic, conversion, cost per acquisition, and lifetime value generated by each channel, and 3) scale the channels that prove to be most effective based on ongoing measurement and testing of not just channels but also brand, design, geography, messaging, and value proposition. Testing should take a holistic approach across all aspects of the marketing.