When I said under promise and over deliver I didn't mean to be cheap and nasty. I meant more along the lines of, don't promise them that you can have it done by tomorrow just to get the job when you know full well that you can't deliver. Say to them it could take a couple of days and work hard to get it done earlier if you can. Also, do a little bit extra just to show them that you care about what you do and not just about the money.
I always remember that one satisfied customer
might recommend you to a friend but
one unhappy customer, will bag you to ten friends. So which is better?