blueish swede said:
ESTA is much easier if you are eligible for the Visa Waiver. It's all done on line and you won't need to visit an embassy.
You need to give them an address for your first nights stay when you go through immigration. They are moving to an electronic system from a papaer system at some airports so you might get a blue form to fill in on the plane to or need to do it on screen at the airport. You will not be able to use your phone in the customs area at the airport so write the hotel address on a piece of paper so you can copy it.
You have to do the ESTA visa and print it off / write down the reference number.
Costs (or did when I last got it) about 14 quid but it lasts for 2 years. I have a green card now so don't need to re-new it.
Yes deffo supply an address at the airport. And don't crack jokes at the airport. They wont get them and will just look at you even more suspiciously than they normally do. Be prepared to have your fingers and eyes scanned too!