I would never have even one sip of alcohol in the 12 hours preceding a flight. Limits are ridiculous when it should be zero tolerance.
I have always had a deep seated mis-trust of 'Pilot Perfect'. Not in any way condoning breaking the CAA rules but have seen tee-total pilots put in a far worse performance than someone who had a couple of beers the night before whilst on the right side of the eight hour limit. Probably the most frightening episode was watching a pilot fly a completely flawless simulator detail right up until he arrived over a beacon for an ADF procedure and turned the wrong way by 180 degrees, heading straight for Mt. Granite. Much preferred flying with pilots who were a little bit either side of the datum at times but always trying to correct it and were concentrating on what they were doing.