Positive reinforcement gives the dog an opportunity to make his own decision by enforcing something good like food, toys or praise for doing a specific behaviour.
With Positive Reinforcement the idea is to add something good, The dog will learn that a good consequence will come from performing the desired behaviour you are trying to achieve and will be more likely to perform it. If you are asking your dog to sit down he will be motivated to achieve the correct response if he knows he will be rewarded. Richer Food Treats can be used for more complex tasks where you need to keep the focus for a longer period of time. The dog will need to be motivated to do so and his normal food treats may not suffice.
Positive reinforcement will increase the likelihood of the behaviour in the future.
Knowing your dogs favourite reward is key to this, most dogs are food motivated, certainly Labradors, who act like they are never fed. Others like a Cocker Spaniel who I walk, has no interest in food but would do anything for you to throw his ball. Others like a French BullDog I know adores cuddles and will do whatever you ask as long as you are offering cuddles and kisses.
So to first sit down we would take the treat over the dogs head and back towards its tail until his bum hits the floor, and then forward in front of him on the ground, guiding the dog so he lies down, this will work well with timid dogs who do not have much confidence as it will build a trust that a treat will be received and no harm will happen.
Using a clicker in conjunction with a treat will help mark the behaviour. with a clicker you click then give a treat and repeat this each time, click then treat, the dog will come to associate the click with something good, so you would ask the dog first, to sit, click immediately when the dogs bum hits the ground then produce a treat, you can also add a cue word after the click “sit” then treat.
Next you would use the treat in order to make the dog lie down, this will take practise. But on each successful move in the correct direction a click and a treat can be given until the dog lies down.
This can be improved upon by only giving the dog a treat at the end of the whole movement, so if you ask him to lie down, the click and treat will only come when the dog has lied down, not if he has sat down first.
We must not reward any other offered behaviours, like paw lifting, extra behaviours should be ignored.
Your rewards can be varied and motivated with a click only, this will keep the dog listening and wondering when the next treat will come. Randomly offer treats after the click, try not to form any patterns as the dog may start to respond to habits and body language. When the behaviour is being performed comfortably then we should vary the environment to proof the behaviour by slowing introducing distractions. A higher/Tastier treat should be offered here to keep your dog motivated and focused on the task at hand so the new behaviours can be generalised in different environments