I've got to say guys (and girls) the best tip i can give anyone on their strokes (esp backhand) is to work on their footwork.
Over the years of coaching and training that I have done with players of all levels, it is really obvious that the people that have good quick feet get into position sooner and better than those who have slow or lazy feet.
Think about it, how many times do you hit a good shot when you have had to move/run for the ball and how many times have you hit a duff shot when the ball has been coming straight too you?
Lazy feet means bad positioning so much so the ATP stats are that over 70% of the unforced errors on the tour are down to poor footwork - FACT!
I feel that all people would play better tennis at the beginning of their tennis carrers if the worked a bit on their footwork.
I feel so strong about this issue that I have written a special report about footwork at http://www.footwork4tennis.com
check it out!