Just came back from Guangzhou/Shenzhen/HK/Macau. Here's some pointer to share:

1. Always have a few credit card tied to Alipay just in case one fails. One of my card got blocked after multiple payment via Alipay and luckily I have a spare one.

2. Expect some surcharge for using CC for payment. Rate for my CC is 60.07 and 60.20 for another CC. For comparison, I exchanged my RMB at 58.80. Small price to pay for convenience (if you change 1000 RMB the difference is just RM12). For big ticket item, I paid cash as it is just one off.

3. I purchased a roaming Sim and as I will be using Hotel Wi-Fi for my video consumption, I purchased a one week VPN (else Google, Facebook etc will not work). I figured a Sim+VPN combo will be cheaper than buying a higher data plan.

4. Majority of the merchants accepts QR payment (Alipay and Wechat), so you can basically go cashless. However some only accepts Wechat so be prepared to pay cash if you only have Alipay.

5. Mobile ordering is super common in China, but you can still order over the counter if you are not familiar. Alipay and Wechat app is a must to cover all grounds.

6. QR in China is a different kind of breed and cannot be scanned using your normal QR reader. You have to use Wechat or Alipay to scan the circular QR and it will direct you to the mini program for ordering.

7. Airport in China only checks your Wh of your powerbank so its fine if you dont have CCC logo (International flight).

8. QR payment is less common in Hong Kong and majority of the popular stall only accepts cash.