1) You can limit the media (billboards, magazines) that tobacco advertisers can advertise on. You can also make it mandatory for companies to add the surgeon general's warning to their advertisment that takes up a certian amount of packaging/advertisment.
2) Age restrict them. 18 year olds hang out with younger kids so you may want to think about having the age restriction be 21. You can also heavily tax tobacco imports or heavily tax the cigarettes themselves.
3) One way is to ban smoking in cars with other people present, you can ban smoking in enclosed spaces.
