Cash are sometimes not accepted, or most shops do not have money for exchange.
Credit cards are rarely accepted, except for Starbucks and hotels. That said, credit cards may be useful for paying a deposit when checking in at hotels.
As of 2023, it is possible to use international credit card to make transactions uing Alipay or WeChat pay. Please follow the instructions in the linked URL, and download and install the international version of AliPay or WeChat app on your smart phone. When you create a new WeChat account, you may need help of someone from China (see below).
N.B. I could link a foreign credit card to an Alipay account from outside China.
To use the free WiFi at the Nanjing (and Shanghai) airport, you need to find a ticket machine for registration (or go to Starbucks). Public WiFi is not ubiquitous in the city.
If you use G-mail, set up a mail-forwarding, another e-mail account or VPN before coming to China.
The SIM card for travelers (which can go across the Great Firewall) is not sold in Nanjing. If you want to use your mobile, purchase a SIM card for travelers before coming to China. Such cards can cross the Great Firewall, but will become invalid after several days.
N.B. The Chinese firewall applies to the mobile data using Chinese SIM cards. If a Chinese SIM is used outside China, one cannot use Google (except for Google Map App)
Limited messenger apps work in China, when you need a quick chat (e.g. to open the gate).
Not many people in Nanjing speak English. However, they carry mobile phones, and may have installed translation apps.
Information in English can be found at e.g. Wikitravel, Nanjing Municipal Tourism Commission, Nanjing city
Online magazine: The Nanjinger
Small restaurants do not have toilets. There are many public toilets on the street, though likely to have no toilet papers. Buy it and bring your own.