[RottsNScotts]

Make sure he is really, really used to being in his crate for long periods and used to having it moving. For example, if he has only been in his crate in your house, put it in your car and go for a fairly long drive that has turns, stops and starts, etc. Get a friend/significant other to help you pick the crate up while he is in it and move it a short distance - DON'T drop it! Have some friends that do not know him or don't know him well look briefly at him while he is in his crate. Make sure he behaves! Have one of these people go over him briefly with plastic/vinyl gloves on (some TSA employees do this!). Take him places that are busy and noisy. If you are going to pull him in his crate to the check in desk, practice that.

I found it can also make him more "personable" to the baggage handling crew if you put his picture, call name and a little paragraph explaining that this is his first flight on the top of the crate. Seems to make them more understanding if he is showing stress or is unhappy.

And most of all, YOU approach the whole thing calmly and confidently. Give yourself even more time than the usual 2 hours to check in as one frequently gets an agent that has not checked a dog in before! (I swear, Alaska, Frontier and Delta ought to PAY me for the training their agents get when I arrive!)