We went in August and after reading up on it (Facebook NYC groups are amazing).
Based on reading we thought 15-20% appeared the norm. We found if you pay by card, in restaurants, then the machine gives you choice. It was usually the 10%, 15%, 20% or 25%.
To be honest we never chose 25%! It took a while to get used to but we started basing it on our experience. Go to Five Guys, you get up to order and then get up to collect. They got less as there wasn't table service
We went to a mall and had lunch, it was like Bluewater etc. Choose what you want and take your tray, no tip.
Kids wanted a bubble tea, was sooo much money but their choice. There was an option tip jar. The servers were great so I put a couple of dollars in.
I think it gets easier as you go along. If you want your room cleaned in a hotel. Changer the sign and leave 5-10 dollars. I forgot the first time and they took all the soap and toilet roll! Got more from reception but learnt a lesson. We then turn the sign to do not disturb and gave £10 on the last day.
Tipping is difficult and I think we found as British people it's sometimes embarrassing and then we are uncomfortable. Some of our tips were bigger, some people really make your experience better!
We mostly paid by card, Chase but apparently Revolut is good too. We needed more cash than I expected. Thinks like tips for the maid, also my car didn't work buying the week long metro card. Luckily I had enough cash for 5 of us at $30ish each!
Have a lovely trip, it's a great city. We go to London a lot and thought it would be similar, it's nothing like it!