Updated: Aug 3
Puppies (and older dogs) don't automatically know how to walk on a lead - this is not a natural behaviour for dogs in the wild.
When they are young, they often stick close to our side. As they grow and become more independent, they may wander off to explore.
Have some yummy treats in your pocket when walking around the house and backyard and start treating when your puppy is next to your leg - this will become the point puppy will want to return to.
Dogs can of course learn to walk on either side of you but it is often easier to start with one side. Practice this at home without the lead then add a lead and keep it loose. Change direction before your puppy starts to pull. Build the foundations at home before expecting your puppy to do this out in the big wide world with lots of distractions.
You may want to have a longer lead to allow your puppy to sniff. Puppies need to sniff so it's a good idea to teach a 'go sniff' cue and give your dog permission to sniff when it is safe to do so.
Happy training! Toby