If you are unsure of the value of knowing and using Greek and Hebrew, or if you could use some more encouragement in the task I highly recommend a little piece written by Scott Hafemann for the Southern Baptist Journal of Theology back in 1999. The piece is written in response to the question:
“Is it genuinely important to use the biblical languages in preaching, especially since there are many excellent commentaries and pastors will never attain the expertise of scholars?”Hafemann’s response is excellent! The rest of the article also contains responses to similar questions about the value of church history, etc. by people like Timothy George and Don Carson.