Try to leave plenty of time for checking in at the airport.
Always reconfirm your flights before setting out for the airport (do this about 24 hours before time of travel)
Check Duty Free allowances carefully particularly on EU destinations.
Try to book your flights outside of peak hours, in order to avoid busy commuter routes and congestion at the airport.
Do not drink too much before boarding the aircraft, as alcohol and cabin pressure cause enhanced dehydration. You are also unable to use the toilets until the aircraft is airborne and at a safe altitude for the seat belt sign to be taken off.
Check with the airline you are traveling with, as to the availability of telephone and lap top power points on board.
Leave contact details for yourself either with someone at home or somebody in the office in case they need to reach you in an emergency.
A phrase book is always handy - remember, not everyone speaks English.