Once you've sorted out your flights or ship crossing get your travel insurance - it will cover you if anything goes wrong before your trip starts so there's no benefit in leaving it to the last minute. If you're taking laptops and phones you might need additional cover.
2. Esta visa
Next on the list is the Esta visa waiver which costs about $14 - you can pay with a debit card (it implies you need to pay with a credit card but I managed on a debit one) or PayPal. Watch out for fake UK versions (one or two are under investigation by the Advertising Standards Authority for misleadingly claiming to be of use). Only use this website - https://esta.cbp.dhs.gov/esta/
You'll need your passport number and the address where you'll be staying (eg hotel) but you can also quit the application and return later - keep a note of your application number which is automatically generated.
When you arrive at the US airport if it's your first visit to the US you'll probably be directed through the 'first visit on an Esta' passport check.
I flew with Virgin Atlantic and the option for at-seat charging was an odd-looking small hosepipe affair that required a UK to US adaptor to work, fortunately I had one in my carry-on bag and was able to lend it to someone else who needed one.
If you make the same journey(s) I made you'll leave from Terminal 3 at Heathrow (the Paddington Express train will take you to Terminals 2 and 3 at the same station and you can just follow the signs for T3) and arrive at Terminal 4 in JFK, then reversed.
I got travel money from my bank - I'm sure you can find cheaper places to get it but it's super convenient at your bank. With smaller branches you might have to give a few days notice so that they can get the dollars but I got mine from the large one at Strand, Trafalgar Square. While in the bank I also let them know that I was to be in New York on the days of my holiday so that if my debit card was used while there they knew it was likely to be me and not some scammer.
For this trip I also got myself a Credit Card in case I needed to use it but I haven't. Last time I got one was for a cruise holiday where I needed it to pay for incidentals (they didn't go for debit cards).
You can use Google Maps Streetview before you go, or once there, to see what your locality will be like, and make note of subway and bus stops. There's a nice foldable detailed map of the metro system which my hotel gave me - if you're self-catering I'd recommend asking a hotel receptionist for one anyway. I didn't spot any at any of the stations I visited oddly enough. I used CityMapper on my phone to get directions.
6. Local travel
New York taxis are mostly much smaller than London cabs and quite useless for sightseeing. The two I was in were more like regular cars (not the four seat arrangement with a large gap between). You're very close to the glass partition and if you're on the passenger side the chances are high that you'll have a medium-sized TV in front of you advertising crap at you. It's possible to mute the sound at least but there's not much window space to see what's in front of you so a bus is better. But the cabs are still pretty cool.
A weekly Metrocard costs ~$32 and lets you have unlimited subway and bus journeys. You just swipe it and push the barrier. The graphics of the card looks very much like Weetabix.
I was staying in Brooklyn so on the return journey I took the A train going to Far Rockaway or Rockaway Avenue and changed at Howard Beach for the AirTrain to JFK Terminal 4. There's a slow train and a fast one but both seem to go to Howard Beach, phew. I took it from Jay Street Metrotech and this is the CityMapper journey using the web browser version.
8. Mobile phone
Before I left I got my pay as you go phone unlocked so that I didn't have to spend ridiculous sums of money on calls / texts to UK while in the US. If you've got a contract yours probably won't be that expensive but worth checking with your provider before you go. I got a US sim card which let me make US calls only, but I was also able to communicate via WhatsApp and Twitter. It was also my first experience of 4G, having only access to 3G at home.
I was surprised to see, at JFK airport on my return, that there are vending machines that sell pre-paid sim cards with different options, though it turns out from looking at them that my in-shop deal was pretty decent.
9. Software support
I use WorkFlowy for making lists (eg for packing or tasks) and Evernote to record info about my trip. I have sections for flight, travel documents (passport / visa), hotel details and packing. Both sync with my phone. I also tag emails in Gmail and keep them in a dedicated folder (before you leave make sure they've synced / downloaded to the right folder). While here I used CityMapper on my phone and switched cities from London to New York (it automatically recognises if you're in a different city and suggests this).
I also kept an eye on the weather app on my phone which told me that New York was going to be both much warmer and much colder than London, so I could pack accordingly.
10. Paper-based support
I'm naturally fairly chaotic so to impose some order I use a clipboard and draw columns on a bit of paper. A small one on the right is for anything that needs to be done or bought in advance of leaving and I have two larger main ones, one each for the bags I'm packing. I have been using WorkFlowy for so long that I now have a very good generic list of things to pack which I adapt for each trip. Once I've packed an item in the bag I write it on the paper (handy for double-checking I've not lost anything on the return journey). I'm afraid I'm neither relaxed nor carefree about holidays ;)
This is highly personalised to me, but here's the gist of what I packed.
- Spare shoes (always nice to have another pair to change into if you can carry them, if not a pair of insoles can be nice if you're doing a lot of walking on your visit)
- Spare pair of jeans
- 'Smalls' - socks and the like - the longer you're away the fewer of these you can pack as you can wash and dry them. For a short holiday my mantra is 'plenty'. Most of them fit into the spare shoes rolled up
- T-shirts - if just a few I leave them flat, if more I roll them
- Leggings / thermals
- Wash bag (deodorant, nail scissors are useful for all sorts of reasons but best kept in checked in bag unless blades are very small)
- a bag to put laundry in
- bit of A5 paper (A4 folded in half!) with my name, phone number and email address saying who the bag belongs to - handy if it gets lost or there's a dispute ;)
- Flight info
- Hotel contact details so that I can give it to the taxi
- Pens / Pencils and writing material
- Maps of New York
- Reading material
- Mobile phone charger, cable and UK to US adaptor
- wet wipes / plasters / ibuprofen
- spare t-shirt / underwear in case main bag goes AWOL
- laptop plus charging cable
- Snacks / chewing gum / water
- currency of country being visited (home country currency is in my pockets until arrival)
- toothpaste / brush (8 hour flight!)
- Clothes, obviously
- Coins in one of those plastic bank coin bags for ease of plonking on tray at security
- Bank cards / travelcard / keys (moved to carry-on bag once on flight)