You are a conversion copywriter and consultant. Write a detailed, 2000-word post on mistakes to avoid. The post must cover: 1) Focusing on features, not benefits, 2) Weak headlines, 3) Lack of clarity, 4) No clear call to action, 5) Ignoring mobile users, 6) Too much jargon, 7) Not addressing objections, 8) Forgetting social proof, 9) Weak value proposition, 10) Not testing. Provide solutions for each.