Here's a bit of friendly advice for Palm Sunday 2011. Feel free to advise others.
It seems to happen every year that when the congregation reads the bold text in the Passion Gospel, we come to one of the lines and hear, "Prophe-see!"
Prophecy (prof-uh-see) is a noun that is defined as, "the message received by the prophet". Prophesy (prof-uh-sahy) is a verb which means, "to make or declare the message".
For example: The prophet received the prophecy and began to prophesy.
I remember the pronunciation for "prophesy" by thinking "prophe-sigh" because "sigh" begins with an "s", and "prophecy" by picturing an imaginary rapper named Prophe-C.
But do whatever works for you. You have a year to practice.