I am so glad you used Michael Clarke as your example, those people who say Phillip Hughes is awesome are wrong (!) Clarke is the man.
Firstly away from cricket try some SAQ work with ladders, try to quicken up your feet.
second, as mortimer says, good footwork stems from wonderful balance, keeping your eyes level and head still.
It is really important that you let your eyes lead your feet, not the other way around. You are not getting your feet to the pitch of the ball, you are getting your eyes over the ball.
Finally as practice, using an old tennis ball practice by throwing it up and moving your feet to hit the ball ont he second bounce into some netting. not just through the offside, but through mid on too...
Sorry if I have repeated what mortimer has said above a little, but he is right!!