Also, try to ensure you are as close to 90deg (perpendicular) to the window as possible - this helps to cut down on both reflections, and the nasty effect of the glass to make the shots look "hazy".
You will almost certainly have to correct for a bad colour-shift when you get home. Many terminal windows look clear to the naked eye, but when really they are often VERY tinted. At Stansted for example, it is always necessary to remove the heavy green tint (note the green windows in the opposite pier):
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Photo © TZ Aviation
Sometimes (when shooting at an angle less than 90deg), you can hold a hand or something up to the window to cut down on stray reflections.