Off the top of my head:
Don't show up drunk or smelling of smoke or with chewy.
The interview begins outside the reception area, so to speak, so take something serious to read in the waiting room.
Research the company and ask appropriate questions.
If you're offered a drink, don't make a difficult choice.
Be prepared for dumb "personality" questions - "Why is the best shape for a manhole round?", "Why are you applying for the job?"
Written CV with minimum details and relevant qualifications - eg. First Aid certificates. If you're sending it off to the place, write a cover letter to introduce yourself.
At the end, say thankyou and shake hands.