You want to focus on stretches where you're not loading the calf muscles with work. So the common stairway stretch is something to avoid, because your calf has to do an isometric contraction just to be in the correct position. Remember you'll only actually stretch the muscles after the initial resistance has worn off.
So avoid this type of thing:
This is the type of thing you should consider doing, but stick a block under the balls of your feet to raise your toes slightly. That helps a lot.