Make ONE of my shots significantly better by practicing it for 500 hits / month outside of regular matches, either with a pro, on the ball machine, or against the wall (serves can be practiced alone on a court). There is no substitute for time on the court. Focus on one shot and then focus on a particular aspect of that shot.
For example, concentrate on getting more spin on your forehand. Do not worry about hitting it in, after all, that is not the goal you’ve set in this example. Do that relentlessly and over the months you will see it improve slowly in your matches and eventually, the ball will start falling in with more spin. Remember, you cannot improve if you do not accept that initially you will be terrible at it. Just keep going. Keep track of how many balls you hit every month, and total that at the end of 2012. You should have hit at least 6000 practice shots on that one shot and will hopefully see a difference. If not, go see your pro and find out if you are practicing it correctly, then get back to work in 2013!