Before training your dog to heel' you must be sure, he/she has learned three other commands. The first is come', the second is sit, and the third is come to heel'.
What is come to heel'?
That is the idea that you want your dog to not only come and sit, but you want him/her to go to your left side and sit waiting your next command, which is heel'.
If you taught your dog to end up facing you and sitting when you called him/her you are ready. With a leash on your friend and him/her sitting facing, you, command "Come to heel". Of course, the first time you say that your friend will smile and you and ask if you are out of your mind. If you are holding the leash correctly, you will have the end and all extra leash in your right hand. When you say "come to heel" you tug on the leash and lead your dog to your right side then pass all the leash behind your back, to your left hand. You must guide your dog all the way the first time and give him/her the sit command immediately when she/he is in position.
The correct position is with your dog sitting at your heel. With your left hand passing the leash to your right, in front of your body, you should be able to let your arm drop and your hand should be in front of your medium sized dog's face. A larger dogs nose will be anywhere from your wrist to your elbow depending on how tall he/she is when sitting. A smaller dog will be below your hand but you should be able to look down and see her/him sitting behind your straight down hand. In a smooth transition from come to sit to come to heel the dog will sit facing you then when commanded will walk around you and sit on your left side.
Do not try heel until the' come to heel' is well learned.
With your dog having followed your direction to come to heel', he/she is ready to heel'. Your dog is sitting on your left side waiting for what comes next. This is when the leash needs to be rearranged, in your hands, if you still had to give a little reminder. Most leashes have a loop at the end. The safest most secure way to hold the leash is with your right thumb stuck in the loop and the rest of the slack of the leash folded neatly in the palm of your right hand. The left hand is free to hold the leash closer to the dog and for petting your friend when she/he does as she/he has been asked.
Heel is only difficult in that the human has some bodywork to learn as well. When you command your dog to heel', say his/her name. "Jackson, Heel." Now is the hard part, you, human must remember to step forward with your left foot as you begin to walk. This is an essential body hint to your dog that you really mean what you say.
Now, the first time, Jackson' has no idea what is up, he may, if you step out correctly, just follow without realizing that is what is expected of him. But, probably not. If he does, praise him like crazy. If he doesn't you don't have to do anything but make sure you keep hold of the leash, you will push against it with your legs and this will deliver a tug that should get Jackson' going. If not let out the leash a little and gently tug in small jerks. This will be a little annoying and will get Jackson' going.
The ideal position of your dog while walking is right there at the heel. But, that is usually a long way off. If you remember to start with your left foot your left leg will push on the lead and give your dog the hint. That is the first goal. When you command and start walking, he should walk too. The next step is to get him at your heel. If he lags, give gentle tugs on the leash until the very second he gets up in position then stop and let the leash slacken. He'll probably drop back again just calmly tug until he catches up and say good boy'. Many dogs hurry ahead. Let them go to the end of the slack in the leash then give a quick jerk and say NO'.
When they move back beside you, welcome them. "Well there you are, good boy". (Or girl you know which)
I have one dog that took three sessions to get a decent heel. I had one that never got it. I have one that took more than ten sessions. If you have been training your dog you should know by now about how long it will take him/her to learn this new trick.
But, you're not done it's nice to be able to stop and know what is expected from your dog. This is the halt' command and is needed like brakes on a car. When you want to stop you say your dog's name and halt' take two more steps, immediately say sit' and if your dog has been trained well he will sit immediately.
Make much of your dog. Tell him how wonderful he is and in the beginning give him a small treat.
When you put it all together, you will have a safe walking companion for many years. The question of why train your dog to sit when you stop has come up often. This is a safety feature. It makes sure that you can stop him or her from jumping away from you in an emergency.
It gives you that couple of extra seconds to decide how to protect yourself and your pet.
Here is what it will sound like when your dog is completely trained. "Jackson, come." Jackson arrives and sits facing you. "Good boy, Jackson, come to heel." Jackson obediently walks to your right around you to your left and sits, again waiting for your next command. "Jackson, heel." You will step out at the same time with your left foot and Jackson will stand and walk forward. When it is done right you can reach out while walking, pet your companion, and tell him he's your best friend. When you see something you want to look at you say "Jackson, halt," and he should stop beside you and sit.
Why the left foot? It's the whole body language thing and you are preparing him for the stay. In the future you will want him to stay while you pick up a dropped item or mail a letter, etc. With the stay command you will walk away from Jackson' with your right foot so he understands that he is to stay, not heel.