Fortunately there is an answer to the question "Where Do i Start" in the very first book of Proverbs. In the Message, Solomon tells us:
Next time that the words "I don't even know where to start" pop into your mind, I hope that this verse does as well. Start the to do list with God -- a short prayer, a reminder that He's got you and that with his strength, wisdom and courage, you can accomplish whatever it is he has planned for you today.
Just that one thought makes everything seem a lot more manageable, doesn't it?