As a coder turned tech startup entrepreneur a few decades ago, I had to learn marketing, advertising, PR and branding from scratch. Fortunately, I had some kind early mentors who were old-school agency types with tons of experience. The single best nugget was from a grizzled Mad Men-esque pro who made it simple. Put 3 things into the first ~3 sentences: 1. A clear, yet mom-level, "What it is", 2. a more advanced "Why it matters", 3. At least one thing that's new, different and important - which is NOT true for the three closest competitors (or our last version). The pass/fail for any ad, landing page or PR was showing drafts to different strangers and testing if they got those 3 things in the first ~15 seconds. If they didn't he'd say, "They're not dumb - your marketing is dumb."

When I complained it was hard, if not impossible, to do that. He dropped the killer line: "Then you don't have a marketing problem. You got a product problem." Over sandwiches he clarified, "You're the genius... just pick problems and build your thing so it makes those three sentences easy to write." He basically thumbnailed a master class in category selection, positioning and differentiation in one lunch. Solid gold - which I've shared with dozens of people in the decades since.