My daughter's cat is a seasoned air traveler. I am assuming in-cabin.
Make your reservation ASAP as most flights only allow 2 pets on board.
Put a copy of the health records (check to see what is required for each state you takeoff or land in) in the pocket of the carrier. Put several cheap hand towels in the bottom of the crate and plan to put them in a ziplock bag (put several in the side pocket). You can toss the bag in the trash, if you want.
Give the cats access to the crate for several weeks before the trip. Mine actually like to sleep in it.
Get a harness and leash and get the cat used to it before the trip. You have to take the cat out of the carrier and walk through the metal detector. No way would I trust a collar only. My daughter's cat dive-bombs into the carrier after it is goes through the X-ray machine.
Skin kids - Jason, Kevin, Allison
Canine kids - Bennett & Bailey (always in our hearts), Riley, Banker, Rogue and Boz
Feline kids - Zoey, Talley and Abra