This can be as easy or as difficult as you like. Tell people you smoke marijuana, where's the shame? (over 40% of your fellow Australians have tried it!) Do not accept the judgement you are sure to recieve. Show them through behaviour and deeds that smokers are not accurately stereotyped in the media. Explain your decision to them, refute the common misinformation.
Another good avenue here is the press, use the media to criticise contradictory sentencing practices, tell the town your not happy about the Gestapo tactics employed by our Police, letters to the editor in small country towns can cause quite a stir! Raise the awareness of the hypocrisy of prohibition at every opportunity.
That won't work I hear a few of you moan from time to time...
Yes, it will work, here's the proof...
Gays. Yes the proof that this method of changing the opinion of your average Aussie works is right there. The word 'poofter' died a sad and lonely death because of the shift in public opinion when they came out of the closet.
If the public perception of homosexuality can be changed, then marijuana should be a walk in the park.