booking a JR reserved seat the week trains actually sell out

for the Tokyo-side JR East lines. steps in order, in the order I actually do them.

01
wifi in some stations is bad enough that setting up an account there is miserable
02
Register with your passport number and an email you'll actually check
03
add a credit card, and have a backup ready
not every foreign card goes through on the first try. mine failed on a Amex once and worked fine on a Visa two minutes later
04
search by the exact station name, not the city name
typing a region name sometimes defaults to the shinkansen stop instead of the local JR station you actually want. check it before paying
05
reserve the seat as soon as the search shows availability
good windows (aisle near the luggage rack) go first on weekends heading toward onsen towns, especially in autumn
06
pay immediately once you've picked a seat
hold only lasts a few minutes, I've lost a seat to my own slow scrolling before
07
link the reservation to your IC card at a ticket gate machine before boarding
off-peak this takes 30 seconds. do it the moment you arrive at the station, not right before your train
08
screenshot the QR code anyway
in case the platform has no signal when you need to show it

Or start a list of your own. Free, it takes a minute.