David Welch, president of Ben Hill Roofing and Siding Co. in Atlanta, detailed some of his company’s most effective marketing strategies, but only after taking the audience on a tour of some recent marketing failures. His goal: to help Best of Success attendees learn from his mistakes as well as his successes. “I don’t know about you, but I hate to waste money on marketing,” said Welch. “I don’t mind spending it, but I sure mind wasting it.”