Shifting is always tricky and you will find the paces where it works the most for you.
Get ready to drop while learning (wrist guards and knee pads will help).
And as already said: the challenge is in the mind: keep your focus and do not let the failures get to you.
For the shifting itself, the type of shoes and even experiments with accessories at the ankle bone, you will find plenty of feedback in the Schlumpf main thread: http://unicyclist.com/forums/showthread.php?t=81914