There are a few things to avoid in selling that will enable you to grow and keep customers. They may seem obvious.
1. Don´t lie. Being honest in life and with clients and customers is critical. For one thing, if you don´t tell the truth, you may have trouble keeping your "stories" straight. Once I had an employer who would create stories about why the product hadn´t been delivered. "The truck jackknifed in the Rockies" was the story once, and then it became something else. Truth reigns. Use it.
2. Don´t promise what you may not be able to deliver. Being a person of your word is one of the most important characteristics you can have. If you always do what you say, people will follow you from company to company — career to career.
3. Don´t focus on your competition´s weaknesses — always come from a position of strength — your strengths. Regardless of what your competition´s shortcomings are, they don´t really matter as long as you can position what your value is — what your company´s product or service is. Too many companies are looking over their shoulder and not looking ahead. Stay the course — your course. And remember, slinging mud makes you lose ground.