Many frequent flyers may have witnessed or experienced air sickness themselves but were helpless during this time. The following tips can help to minimise the severity or prevent air sickness. 

• Make distance visual references or look outside the aircraft and hold your head still as your eyes (other than your inner ears) send the message to your brain on the direction of the motion. Do not try to read or look at near object in the aircraft.
• Take deep concentrated breathings, open air vents, loosen clothing and relax. Anxiety and rapid or abrupt movements will exacerbate your condition.
• Inform the crew to reduce the cabin temperature if you find that the temperature is warm. As your skin is also the receptor that reports to the brain, and cooler cabin temperature reduces its sensitivity.
•  Seat at over-wing area or middle of the aircraft where it has smaller angle of motion. The wider angle of motion is at the rear and the upper deck of the aircraft.
•  Drink a glass of ice cold Coke or 7up. Through my experience I noticed that the cold carbonated drinks help to relief air sickness quite effectively. Do not eat spicy or oily food.  
• Always get the air sickness bag ready as the smell of the vomit/mess will make others to feel sick too. Do not talk to the people who are experiencing air sick. 

Above all being prepared for the flight/journey is the best remedy. You know your body better than anybody else. If you are susceptible to air sickness, a glass or two of fresh ginger tea before embarking the aircraft will help. There are also many preventive drugs available at the counter or by prescription by your medical officers. However, these drugs may cause drowsiness and impaired your judgement temporarily. As such, crewmembers are not to take them when on duty.