Tips for flying with 18-month old baby?

I took my son on a plane when he was round about that age. I do no that they won t let you take a car seat on the plane as the baby will have to sit on your lap. That's why babys under 2 go free because they dont take up a seat on the plane. i made sure my son had a good sleep before we went so he was a happy chappy while flying. Also take a favourite toy with you so he can play with it on your lap.. hope it all go s well. x