Here's a great example of an anti-smoking campaign aimed at young people - UP2You

The Up2You Campaign by the Public Health Agency

Notice how they thought of their target audience and how the campaign was spread across different media: for instance, teenage magazines, the website with its post cards, a TV ad, poster, etc.

Notice also the importance that the Public Health Agency attach to what the target audience thought of their campaign in the comments evaluating the campaign.

Other helpful examples
http://smokefree.nhs.uk/ scroll down to the resources link if you get the first page by error. There are lots of campaigns here with resources attached.

For an older target audience take a look at this campaign against smoking by "Aspire" from Health Scotland.
Aspire poster advert

Anti-bullying campaign
YWCA anti bullying campaign