How I taught Heel:
Slip collar on and leash attached to it. Place dog on left side in postion and say heel walk off leading with left leg. I also gave the hand signal that we use! If the dog leggs behind I called him up and when he got into the heel I said Heel again. If he rushed ahead I just did an abrupt turn and again said Heel. Took about 20 mins and now whenever I say heel, he heels on or off leash.
I did not knee the dog on the turn, I just felt that was not neccesary and he learned fast with me just turning but some people will advise kneeing or knee blocking the dog when you turn towards them.
Storm who only knows sit, now knows heel too.