Your clothing choice while flying on an aircraft is very important
. Firstly you've got to be able to feel that you will be comfortable while sat in the clothes for a number of hours.
Don't wear clothes like you're going to a job interview. In the past businessmen of course would have dressed up for a flight. It was a fancy and special occasion, and the stewardesses would similarly be dressed up. But no longer do you need to feel like you should follow such old and date convention. These days, on flights from London to Singapore or flights from Tampa to Cancun you should not feel guilty about wearing pyjamas or the most comfortable clothes you can find. After you all, it's you who is travelling so don't feel like you should be dressing up for the occasion.
I personally like to wear baggy pants and a loose shirt. It's important to remember that the cabin can be very cold or way too hot sometimes, and that you need to be prepared for every eventually. You also want to make sure that you are wearing shoes that are suitable for the flight. Shoes that are comfortable and can be slipped on and off when you want to sleep or relax a little more are especially good aircraft wear. They are twice are good in fact because you can actually also benefit from this sort of footwear when in the airport. You are able to slip on and take of the socks for the security officials who are manning the security clearance zone. They often want to x-ray shoes too, so wear something that can be taken off on and on