COMMITMENTS
Activities do not run on a clockwork schedule. Innumerable problems are encountered involving a chain reaction. But when you make a commitment give sufficient buffer and stick to it. If you cannot keep up to a commitment then inform your customer and explain. If you throw an unpleasant surprise at him he is sure to get mad. Keep him informed and he would understand and accommodate.

BITE AS MUCH AS YOU CAN CHEW
Make promises you can meet and meet promises you have made, live up to them, do something more than expected and you have satisfied customers for life.