We'll give it a short airing here since you asked nicely and didn't insist... We'll move it once the forum gets into the busy time but at the moment it's quiet so it can stay for a bit.

1) ABSTAINING FROM ALCOHOL - I do abstain, at least for the day before the flight, on the day of the flight, and the day after the flight. In my case for vanity reasons of avoiding horrifically dry skin which I find gets worse if I had anything alcoholic. If I feel tired or run down, I avoid it for longer. My husband who used to fly a lot (although not any more) does exactly the same. He still catches everything going, however.

2) SUPPLEMENTS - not really. I try to eat more fruit and veg but it doesn't necessarily mean it's doing me any good in terms of avoiding catching things. My husband who used to fly a lot (although not any more) does exactly the same. He still catches everything going, however.

3) KEEP AWAY FROM OTHER PEOPLE. Now this is what I found to be most effective way of avoiding catching a cold etc. In other words, don't fly Y where you have a higher chance of being closer to other people who might be coughing/sneezing etc. and you have no escape. At least in F you are further away from others But seriously, keep away from people who seem ill as much as you possibly can.

4) SLEEP - what sleep?! The less of it I can get away with the better But grab it whenever you can. I sleep in all sorts of places including my office chair (usually not the office floor - that's what I used to do when I was younger but I need more comfort now). When you have mastered the art of napping whenever and where-ever including being rather upright on BA short haul well before take-off, then you've got it cracked But see what your body wants to do. Avoid resorting to drugs if possible but if you must, do so under appropriate medical supervision. Try not to use alcohol for sleep adjustments - it usually renders your sleep quality poorer. Alcohol is to be enjoyed, not for use for medicinal purposes!

5) QUEUE AVOIDANCE - as much as you can, for reason 3) but also because it wastes your time and not always good for your mental health if you are feeling like you're wasting your life away stuck in a queue.

6) 'HEAVY' FOOD AVOIDANCE - it's easy to overeat when you're bored stuck in an aluminium tube but eating light, tasty food usually works better overall (including for avoidance of having to spend more money on clothes because they no longer fit) and helps you to sleep better than stodgy, rich food.

7) HAND WASHING - even if you can't see dirt because BA happens to have cleaned the plane really well, germs are still there. Make sure you wash your hands frequently and avoid touching eyes, nose and mouth if you have touched much at all. Paranoid? Yes maybe, but it's usually a good idea to keep good personal hygiene. Remember to wash your hands before eating. If you are trapped in a window seat and you want to avoid disturbing your neighbour, carry sanitising gel.