First time flying

I need some advice I'm taking my LO on her first flight in December....going to see some family. What is some advice fo2e a smooth somewhat quiet flight?!? I'm a little nervous that she may have a break down! She has really been a perfect baby in all aspects, calm for the most part has sat through a brodway show like a champ.

****UPDATE***** Thank you everyone for the advice!!! I'm glad to say she did amazing!! Milwaukee airport had a little play are she could run around in and wear herself out before thw flight! I made sure we had plenty of snsks and she was well entertained by all the people on the plane!!