The customer is not always right. You are the technology expert, so act like it. Be professional, but confident. Don't insult clients while educating them. Convince them with facts.
Technologists are their own worst enemies.
Many of us lack leadership and interpersonal skills. Work on them. The computer industry lacks leadership. While there are powerful men with a great deal of money, none are true leaders. Engineers and programmers might follow a Bill Gates or Steve Jobs, but the American public in general does not tolerate such leaders.