I would suggest practising shooting off one foot.  That way when you get the ball you can step back and away from the defender who is defending you.  The other thing to ask is what is your shooting style?  is it from a position that comes down towards the face or is it up high from an extended arm and your shooting arm goes back above your head?  if its the former then working on your shooting style to get it up will also help keep the ball away from a tall defender.  look at some videos online about improving shooting techniques.