Rule #5: ImmigrationNot much to add, there.
I have never met an airport immigration desk that was set up to make travelers feel welcome, but there are various grades of awfulness. Entering the USA today has been compared unfavourably with entering Iran, or the Soviet Union circa 1985. It's a very unfriendly experience, but a bit of preparation helps.
You need your travel documents close to hand during your flight because the cabin crew will hand out customs declaration forms and landing cards/visa waiver forms. This is where the ballpoint pen comes in handy, and the address of your hotel, and your passport number. (I said there'd be an exam, didn't I?) Read the instructions on the forms before filling them in, because there's nothing as annoying as being sent to the back of a queue of 300 shuffling jet-lagged tourists at what your body insists is 3am because you forgot to fill it in in block capitals or something.
US immigration will photograph you with a webcam and fingerprint you. They'll ask intrusive and annoying questions and try to spot holes in your answers that suggest you're lying to them.
Do not lie to these people. They can lock you up and throw away the key. The former US attorney general was of the opinion that they could beat seven shades of crap out of you with impunity, as long as they didn't kill you. Until you clear immigration and customs you are an un-person. Admonitions about being polite and playing by their rules apply doubly here. If you give them cause, they will clap you in hand-cuffs and put you on the next flight home. This is not what you suffered through 8 hours of long-haul travel for.
Go. Read. Learn. Enjoy.