Before beginning this training exercise, let your puppy expend some excess energy. Attach his lead to his collar and remain standing still. Hold a treat in the hand nearest to your puppy, with the lead in the other. Adjust the lead so it is loose, but it should not be touching the ground. Lure your puppy to your side (the side with the treat) using a treat, keep doing this until he remains at your side.
Keep the treats in your hand visible to your puppy, stand straight and hold the treat up out of his way. Call his name until you get his attention. Use your voice-cue and move a few steps forward.
If your puppy is still paying attention to you/the treat, praise him and feed him the treat. Repeat steps 1-3 until you feel confident you are making enough progress to move on.
Begin taking more steps with your puppy walking by your side. If he pulls ahead, refrain from tugging him backwards, instead, stand still and lure your puppy back to your side.
Find a small area where you can hold several training sessions. Make wide turns and reward your puppy with praise and treats frequently. Training has to be exciting for him, talk enthusiastically to your puppy. If he tried to move away from you, keep an eye on the lead. If it appears as though it is about to become tight, stand still and hold the lead firm, so your puppy comes to an abrupt halt. Encourage him back into position before repeating step 2.
As you and your puppy become more experienced at walking together, begin to incorporate obstacles and turns. Change the speed at which you walk to keep things more exciting.