I wouldn't look away, why would someone look away if they were doing nothing wrong? I saw some cop show yesterday where a cop was in his van, saw someone on the street, the person looked away, the officer immediately became suspicious of that and got out. The suspect ran, he was caught and arrested. Be confident and direct, avoid hand to head contact, they look for that. Avoid lighting a cig because they know you're masking the smell or trying to calm your nerves. Why are you nervous? Be cool.