If you saw the sign that states "Save the planet - don't litter" the technique of policy enactment being used is hortatory. This is because they are strongly urging you not to litter.
In terms of policy implementation, hortatory techniques are those that encourage people to comply with a policy by appealing to their better senses in an attempt to make them act in a certain desired way.
This is a technique most useful in public campaigns, such as one to discourage smoking or drinking.
