The document outlines 10 common mistakes made in sales that should be avoided. These include misunderstanding what selling entails, thinking sales skills are innate rather than learned, talking too much and not listening enough, using words that discourage sales, not knowing when to close a sale, failing to close sales effectively, being insincere, neglecting details, allowing oneself to become discouraged, and failing to maintain regular contact with customers. Mastering sales requires learning skills like questioning, listening, and closing sales at the right time, rather than relying on innate talents. Avoiding these mistakes can help lead to success in sales.