Are you passing through the US or staying there? I did not need the ESTA coming from Canada. I took an American Airlines flight and I was required to go through the TSA in the Toronto airport. I was randomly tested for bombs with a swab and patted down, but got through. In general remember they are people doing a shitty job, don't act like a dick. You will likely need to use the body scanner. Make sure your carry on has nothing that could flag a possible check, keep it all in the suitcase. If you are bringing an electronic device on the flight make sure it is charged as they will ask you to turn it on. You have the right idea, don't pack stupidly, don't act stupidly, and you should be fine. Unless you aren't white.