Policy implementation and its challenges

Cconsider a new policy or strategy that you think would be a good idea (and is not being done right now). This could be at the local, national, or even international level. For this policy/strategy, how would it best be introduced? Would it be compatible with existing policies and practices or would those need to change as well? What are the challenges to implementation of this policy? Overall, how much of a challenge do you think implementation would be (and is it worth overcoming those challenges)?