see my above post for technique, but- you artificially increase the baseline readings for neutral questions. you can chill yourself out, but you can't control such things as perspiration, which is affected by the stress of lying and is controlled by the central nervous system... but you can artificially increase your response to neutral stimulus.
I have never had a lie-detector test by the way.... did anyone else hear about a criminal who the police caught by wiring him up to a photocopier, from a colander placed on his head? inside the copier was a sheet of paper that said 'he's lying'... every time the crim said something where they didn't believe him, the policeman got up and pressed 'copy' and, out came the lie-detector's verdict...! he eventually 'coughed', as they say... possibly urban myth...