Worrying about the past or the future isn't productive. When you start chastising yourself for past mistakes, or seeing disaster around every corner, stop and take a breath and ask yourself what you can do right now to succeed.
I've learned that people will seldom let you down if they understand that your destiny is in their hands, and vice versa.
There is a time to provide advice and offer an opinion, and there is a time not to. Don't be too quick to offer unsolicited advice. It certainly will not endear you to people.
Delegating doesn't mean passing off work you don't enjoy, but letting your employees stretch their skills and judgment.
To me, job titles don't matter. Everyone is in sales. It's the only way we stay in business.
Too often, sales reps simply regurgitate their presentations and expect to land the sale. It doesn't work.